NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution

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When Boats Don’t Float: From Sunken Wrecks to Abandoned Ships

Derelict boat in a Gulf marsh.

Ships end up wrecked or abandoned for many reasons and can cause a variety of environmental and economic issues. After Hurricanes Katrina and Rita, thousands of vessels like this one needed to be scrapped or salvaged in the Gulf of Mexico. (NOAA)

The waterways and coastlines of the United States are an important national resource, supporting jobs and providing views and recreation. However, the past century of maritime commerce, recreation, and even warfare has left a legacy of thousands of sunken, abandoned, and derelict vessels along our coasts, rivers, and lakes.

Some of these sunken shipwrecks are large commercial and military vessels such as the USS Arizona in Pearl Harbor, Hawaii; the Edmund Fitzgerald in the Great Lakes; and the recent tragic loss of the 790 foot cargo ship El Faro and its crew off the Bahamas.

These large vessels may be environmental threats because of their cargoes, munitions, and fuel, but many also are designated as submerged cultural resources—part of our maritime heritage. Some even serve as memorials or national historic landmarks. Unless they are pollution hazards, or shallow enough to be threats to navigation or become dive sites, most are largely forgotten and left undisturbed in their deep, watery resting sites.

But another class of wrecks, abandoned and derelict boats, are a highly visible problem in almost every U.S. port and waterway. Some vessels are dilapidated but still afloat, while others are left stranded on shorelines, or hidden just below the surface of the water. These vessels can have significant impacts on the coastal environment and economy, including oil pollution, marine debris, and wildlife entrapment. They become hazards to navigation, illegal release points for waste oils and hazardous materials, and general threats to public health and safety.

Large rusted out ship in shallow water surrounded by corals.

Some shipwrecks, like this one stranded among coral in American Samoa, can become threats to marine life and people. (NOAA)

Most derelict and abandoned vessels are the result of chronic processes—rot and rust and deterioration from lack of maintenance or economic obsolescence—with vessels slowly worsening until they sink or become too expensive to repair, and around that point are abandoned.

Others are mothballed or are awaiting repair or dismantling. If the owners can’t afford moorage and repairs, or if the costs to dismantle the ship exceed the value of the scrap, the owners often dump the boat and disappear. Many vessels end up sinking at moorings, becoming partially submerged in intertidal areas, or stranding on shorelines after their moorings fail. These vessels typically lack insurance, have little value, and have insolvent or absentee owners, a problematic and expensive combination.

Another source of abandoned vessels comes from major natural disasters. After large hurricanes, coastal storms, and tsunamis, a large number of vessels of varying sizes, conditions, and types may be damaged or set adrift in coastal waters. For example, approximately 3,500 commercial vessels and countless recreational vessels needed to be salvaged or scrapped after Hurricanes Katrina and Rita hit the Gulf Coast in 2005. And remember the empty squid boat that drifted across the Pacific Ocean after the 2011 Japan earthquake and tsunami?

NOAA’s interests in this wide range of lost or neglected ships include our roles as scientific advisers to the U.S. Coast Guard, as stewards of marine living and cultural resources (which extends to when these resources are threatened by pollution as well), and as the nation’s chart maker to ensure that wrecks are properly marked for safe navigation.

This week we’re taking a deeper dive into the many, varied, and, at times, overlooked issues surrounding the wrecks and abandoned vessels dotting U.S. waters. As recent events have shown, such as in a recently discovered leaking wreck in Lake Erie and a rusted tugboat left to rot in Seattle, this issue isn’t going away.

First, check out our infographic below exploring the different threats from wrecked and abandoned ships and a gallery of photos highlighting some examples of these ships, both famous and ordinary. Stay tuned for more stories here and at

Illustration showing a sunken, abandonedship sticking out of the water close to shore, leaking oil, damaging habitat, posing a hazard to navigation, and creating marine debris on shore.

Sunken and abandoned ships can cause a lot of potential damage to the environment and the economy. (NOAA)

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Visualizing How Ocean Currents Help Create the Garbage Patches

Plastic water bottle floating in the ocean.

The “garbage patches” are not giant, floating islands of trash, but rather, ocean gathering places for what are mainly tiny bits of plastic dispersed throughout the water column, with some larger items as well. (NOAA)

The data whizzes at NASA recently decided to turn their attention from the sky to the ocean as they attempted to model how ocean currents help drive the formation of the “garbage patches.” From NASA:

“We start with data from floating, scientific buoys that NOAA has been distributing in the oceans for the last 35 years represented here as white dots … If we let all of the buoys go at the same time, we can observe buoy migration patterns … The buoys migrate to 5 known gyres also called ocean garbage patches.

We can also see this in a computational model of ocean currents called ECCO-2. We release particles evenly around the world and let the modeled currents carry the particles. The particles from the model also migrate to the garbage patches.”

Check out their data visualization here:

As you might gather from the visualization, the gyres, where “garbage patches” are located, represent massive, dynamic areas of the ocean that are constantly moving and changing—and as a result, are also bringing trash and other marine debris with them. Rather than giant, floating islands of trash that you can see from satellites (you can’t), “garbage patches” are ocean gathering places for what are mainly tiny bits of plastic dispersed throughout the water column.

Still fuzzy on what the garbage patches are and are not? Check out this video from the NOAA Marine Debris Program:

And tune in to this National Ocean Service podcast to learn what we know and don’t know about the garbage patches and what we can do about this ocean-sized problem:

You can also read about our own efforts to model where marine debris travels across the ocean.

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In Wake of Japan’s 2011 Tsunami, Citizen Scientists Comb California Beaches Counting Debris

Man with clipboard and bag walking on beach.

A volunteer counts and collects the marine debris washed up at Drakes Beach in the Greater Farallones National Marine Sanctuary. (NOAA)

It all started more than five years ago on the other side of the Pacific Ocean. A devastating earthquake and tsunami rocked Japan in 2011, ultimately sweeping millions of tons of debris from the coastline into the ocean. But it wasn’t until June the following year, in 2012, that a 66-foot-long Japanese dock settled on the Oregon coast and reminded the world how the ocean connects us.

NOAA’s Kate Bimrose explained how this event and the resulting concern over other large or hazardous items of Japanese debris spurred the start of NOAA monitoring programs on beaches up and down the West Coast and Pacific islands. She coordinates the program that monitors marine debris in the Greater Farallones National Marine Sanctuary off the north-central California coast.

Thanks to funding from NOAA’s Marine Debris Program, the first surveys in this sanctuary near San Francisco took place in July 2012, a month after the Oregon dock made an appearance. No previous baseline data on debris existed for the shores along this California sanctuary. The only way anyone would know if Japan tsunami marine debris started arriving is by counting how much marine debris was already showing up there on a regular basis.

Training a Wave of Citizen Scientists

Graphic showing an example 100 meter stretch of beach with four 5 meter transects.

Following NOAA Marine Debris Program monitoring protocols, volunteers survey the same 100 meter (328 foot) stretch of beach each month, randomly choosing four sections to cover. Next, they record every piece of trash bigger than a bottle cap in those areas. (NOAA)

To find out how much trash and other manmade debris was washing up, Bimrose trained a small group of dedicated, volunteer “citizen scientists” to perform monthly surveys at four regular California beach sites. Three are located in Point Reyes National Seashore and one is in Año Nuevo State Park, but all are fed by the waters of the Greater Farallones National Marine Sanctuary.

Following NOAA Marine Debris Program monitoring protocols, once a month two volunteers head to the same 100 meter (328 foot) stretch of beach, using GPS coordinates to locate it. Next, they randomly pick four sections, each five meters (nearly 16.5 feet) long, to survey that day. This ensures they cover 20 percent of the area each time.

For those areas, the volunteers record every piece of trash they find that is at least the size of a bottle cap, or roughly an inch long. Having this size standard increases the reliability of the data being collected, providing a more accurate picture of what the ocean is bringing to each beach. NOAA is confident that volunteers are able to scan the sand and find the majority of items larger than an inch sitting on the surface of the beach.

Taking Things to the Next Level

Bottle with Asian characters on the cap.

While volunteers occasionally turn up debris bearing Asian characters, no items reported from this program have been confirmed from the 2011 Japan tsunami. (NOAA)

All of the data volunteers gather—from number of items to types of material found—gets entered into a national online database, which will allow NOAA to determine trends in where, what, and how much marine debris is showing up. Leaving the items behind reveals how debris concentrates and persists on shorelines, information which is lost when debris is hauled off the beach.

While gathering this information is useful, Bimrose admitted to one sticking point for her: none of the debris is cleaned up from these four beach locations.

“We want to be able to remove the debris,” she said. “It’s painful for all my volunteers to be out there and record it and not remove it.” However, the good news is that a June 2015 expansion to this monitoring program has added two new beach locations to the rotation, and after volunteers record the debris there, they pack it out. In addition, Bimrose takes out larger groups of one-time volunteers to those locations and trains them on site, creating a broader educational reach for the program.

Bimrose hopes to recruit local school groups as well as businesses to volunteer. Before each survey at the new locations, she introduces the sanctuary and the monitoring program, while passing around mason jars filled with the trash collected at past surveys to give volunteers an idea of what to expect.

These new monitoring sites receive more recreational use than the previous ones, and at least for the one at Ocean Beach, a heavily used shoreline in the heart of San Francisco, that means finding a lot more consumer trash left on the beach.

From clothes and cigarette butts to food wrappers and even toilet paper, the surveys at Ocean Beach are markedly different from those surveys further north at Drakes Beach, the other new site. There, volunteers count and remove mostly small, hard fragments of plastic that appear worn down by sun and sea, indicating the majority of the debris there is brought to shore by the waves, not beachgoers.

Survey Says

Long blue piece of boat insulation sitting on a table.

A volunteer surveying a beach in the Greater Farallones National Marine Sanctuary found this piece of insulation from an elite sailboat that broke apart in San Francisco Bay in 2012. The debris took two months to travel to a shoreline 60 miles north. (NOAA)

After four years of monitoring and roughly 150 surveys, what have they found so far on the north-central California coast? More than 5,000 debris items recorded in all, which, as Bimrose said, is “a good amount but not too crazy.”

Expanding to six survey sites from four only increases what they can learn about debris patterns in this area. As more data roll in, NOAA will able to outline the regional scope of the problem and see patterns between seasons, years, categories, and locations of debris accumulation. One thing that is likely not to change, however, is that plastic debris dominates. It constitutes about 80 percent of the trash found at all sites.

While volunteers occasionally turn up debris bearing Asian characters, no items reported from this program have been confirmed from the 2011 Japan tsunami. Through other partners associated with beach cleanups however, three pieces of Japan tsunami debris have been confirmed in California. The most recent was a large green pallet with Kanji lettering that landed on Mussel Beach just south of San Francisco. The discovery reinforces the importance of continuing to monitor debris along sanctuary beaches and shows us how items can persist in the ocean for years before sinking, breaking up, or landing on shore.

Another unusual example linking a piece of debris to the exact event that released it occurred in 2012. During a training run for the America’ Cup sailing race, an $8 million boat capsized and broke apart in San Francisco Bay on October 16, 2012. Two months later, one of Bimrose’s volunteers discovered a piece of insulation from that boat on a beach about 60 miles north.

Every month, Bimrose tags along with at least one pair of volunteers for their survey of one of the four “survey-only” beach sites. On one such occasion, one volunteer, an older gentleman, brought along his wife, who was puzzled by her husband’s constant chatter about “his” beach. According to Bimrose, a lot of the surveys could be considered rather clean or even monotonous. But even so, after a day walking and counting with him, the volunteer’s wife told her, “I totally get it, why he comes out here and rearranges his schedule to do this.”

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Surveying What Hurricane Katrina Swept out to Sea

This is a post by Nir Barnea of NOAA’s Marine Debris Program.

Sunken boat next to a house in Louisiana.

Hurricane Katrina’s storm surge, over 25 feet high in places, destroyed houses, boats, and infrastructure along the Gulf Coast, and when it receded, it washed out to sea massive amounts of what became marine debris. (U.S. Coast Guard)

Hurricane Katrina was a powerful storm, one which brings a variety of powerful images to people’s minds: The satellite image of the huge storm moving toward the Gulf Coast, the flooded neighborhoods of New Orleans, damaged boats strewn all over like discarded toys.

But for me, the image I remember most vividly is one of stairways leading to homes no longer there. Driving along Mississippi’s Route 90 from Biloxi to Pass Christian on a hot August day in 2006, I saw dozens of them. They were the only remnants left of the beautiful beachfront houses that once lined that road, an area devastated by Hurricane Katrina’s overwhelming storm surge.

Swept Away

The same massive storm surge that demolished these houses was the reason I was in the region a year after Hurricane Katrina struck the Gulf Coast. The storm surge, over 25 feet high in places, destroyed houses and infrastructure, and when it receded, it washed out to sea massive amounts of what became marine debris.

In the wake of Hurricane Katrina and less than a month later, Hurricane Rita, the marine debris in ports and navigation channels was cleared quickly. However, the remaining debris, outside of navigation channels and in fishing and boating areas, posed a safety hazard to people, damaged boats and fishing gear, and hampered recreation and commercial activities.

To help deal with this debris, Congress appropriated funding in 2006 and again in 2007 to NOAA’s Office of Coast Survey and Office of Response and Restoration to survey traditional fishing grounds, map items found, disseminate survey information to assist with removal, and inform the public.

The project took three years. During the first phase, areas off the coast of Alabama, Mississippi, and eastern Louisiana were surveyed with side scan sonar. The survey teams generated maps of suspected underwater debris items (called “targets”) and placed them on the Gulf of Mexico Marine Debris Project website. We also shared with the public the locations of debris items determined to be a danger to navigation.

In the second phase of the project, our survey covered nearshore areas along the central and western Louisiana coastline. In addition to side scan sonar, survey teams used multi-beam survey technology for major targets, which is a powerful tool that provided us with vivid images of the objects detected.

NOAA, Federal Emergency Management Agency (FEMA), U.S. Coast Guard, and the State of Louisiana collaborated closely to determine which targets were the result of Hurricanes Katrina or Rita and therefore eligible for removal. Many of the targets we detected were actually not the result of these two major storms.

Dealing with Disaster Debris

Overturned boat in water awaiting salvage with another boat salvaged in background.

To help deal with the debris not yet cleared after Hurricanes Katrina and Rita, Congress appropriated funding to NOAA to survey traditional fishing grounds, map items found, and share that information to assist with removal and public notification. (NOAA)

On September 2, 2009, the project partners met in Baton Rouge, Louisiana, for a workshop summarizing the project. Participants provided insights and suggestions for improving the process, which were later gathered into the workshop proceedings [PDF]. We learned many lessons from this project, which should be put to good use in the future.

One of the things I liked most about the project was its collaborative nature. Project partners included two NOAA offices and eight contractors, Coast Guard, FEMA, a host of state agencies from the three impacted states, NOAA Sea Grant, and of course, the general public in the Gulf of Mexico. This collaborative effort did not go unnoticed, and the project received the Gulf Guardian Award for Partnership.

Hurricane Katrina was the first severe marine debris event for the young NOAA Marine Debris Program, established in 2005. It was not the last.

Over the last 10 years, our program, along with other parts of NOAA, have dealt with marine debris from Hurricane Sandy, a tsunami in American Samoa, and most recently, the influx of debris from the Japan tsunami of 2011.

Sadly, this trend suggests more such events in the future. NOAA and other agencies have learned a lot over the past 10 years, and we are better prepared for the next disaster which might sweep debris out to sea or bring large amounts of it onto shore (what we call “severe marine debris events”). Learn more at and

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Resilience Starts with Being Ready: Better Preparing Our Coasts to Cope with Environmental Disasters

This is a post by Kate Clark, Acting Chief of Staff with NOAA’s Office of Response and Restoration.

If your house were burning down, who would you want to respond? The local firefighters, armed with hoses and broad training in first aid, firefighting, and crowd management? Or would your panicked neighbors running back and forth with five-gallon buckets of water suffice?

Presumably, everyone would choose the trained firefighters. Why?

Well, because they know what they are doing! People who know what they are doing instill confidence and reduce panic—even in the worst situations. By being prepared for an emergency, firefighters and other responders can act quickly and efficiently, reducing injuries to people and damage to property.

People who have considered the range of risks for any given emergency—from a house fire to a hurricane—and have formed plans to deal with those risks are more likely to have access to the right equipment, tools, and information. When disaster strikes, they are ready and able to respond immediately, moving more quickly from response to recovery, each crucial parts of the resilience continuum. If they prepared well, then the impacts to the community may not be as severe, creating an opportunity to bounce back even faster.

Having the right training and plans for dealing with disasters helps individuals, communities, economies, and natural resources better absorb the shock of an emergency. That translates to shorter recovery times and increased resilience.

This shock absorption concept applies to everything from human health to international emergency response to coastal disasters.

For example, the Department of Defense recognizes that building a culture of resilience for soldiers depends on early intervention. For them, that means using early education and training [PDF] to ensure that troops are “mission ready.” Presumably, the more “mission ready” a soldier is before going off to war, the less recovery will be needed, or the smoother that process will be, when a soldier returns from combat.

Similarly, the international humanitarian response community has noted that “resilience itself is not achievable without the capacity to absorb shocks, and it is this capacity that emergency preparedness helps to provide” (Harris, 2013 [PDF]).

NOAA’s Office of Response and Restoration recognizes the importance of training and education for preparing local responders to respond effectively to coastal disasters, from oil spills caused by hurricanes to severe influxes of marine debris due to flooding.

Coastline of Tijuana River National Estuarine Research Reserve in southern California.

Within NOAA, our office is uniquely qualified to provide critical science coordination and advice to the U.S. Coast Guard, FEMA, and other response agencies focused on coastal disaster operations. The result helps optimize the effectiveness of a response and cushion the blow to an affected community, its economy, and its natural resources, helping coasts bounce back to health even more quickly. (NOAA)

In fiscal year 2014 alone, we trained 2,388 emergency responders in oil spill response and planning. With more coastal responders becoming more knowledgeable in how oil and chemicals behave in the environment, more parts of the coast will become better protected against a disaster’s worst effects. In addition to trainings, we are involved in designing and carrying out exercises that simulate an emergency response to a coastal disaster, such as an oil spill, hurricane, or tsunami.

Furthermore, we are always working to collect environmental data in our online environmental response mapping tool, ERMA, and identify sensitive shorelines, habitats, and species before any disaster hits. This doesn’t just help create advance plans for how to respond—including guidance on which areas should receive priority for protection or response—but also helps quickly generate a common picture of the situation and response in the early stages of an environmental disaster response.

After the initial response, NOAA’s Office of Response and Restoration is well-positioned to conduct rapid assessments of impacts to natural resources. These assessments can direct efforts to clean up and restore, for example, an oiled wetland, reducing the long-term impact and expediting recovery for the plants and animals that live there.

Within NOAA, our office is uniquely qualified to provide critical science coordination and advice to the U.S. Coast Guard, FEMA, and other response agencies focused on coastal disaster operations. Our years of experience and scientific expertise enable us to complement their trainings on emergency response operations with time-critical environmental science considerations. The result helps optimize the effectiveness of a response and cushion the blow to an affected community, its economy, and its natural resources. Our popular Science of Oil Spills class, held several times a year around the nation, is just one such example.

Additionally, we are working with coastal states to develop response plans for marine debris following disasters, to educate the public on how we evaluate the environmental impacts of and determine restoration needs after oil and chemical spills, and to develop publicly available tools that aggregate and display essential information needed to make critical response decisions during environmental disasters.

You can learn more about our efforts to improve resilience through readiness at

Kate Clark.Kate Clark is the Acting Chief of Staff for NOAA’s Office of Response and Restoration. For nearly 12 years she has responded to and conducted damage assessment for numerous environmental pollution events for NOAA’s Office of Response and Restoration. She has also managed NOAA’s Arctic policy portfolio and served as a senior analyst to the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling.

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How to Keep Your Belongings From Becoming Trashed by Hurricanes

Destroyed dock and debris along a populated canal in Louisiana.

No matter the size of the storm, you and your family can take steps to reduce the likelihood of your stuff becoming storm debris. (U.S. Coast Guard)

Winds, heavy rains, flooding, storm surge. Hurricanes and other powerful storms can cause a lot of damage, both to people’s lives, of course, but also to the surrounding land and waters.

Docks, storage tanks, and buildings can be ripped off their foundations. Oil drums, shipping containers, and lumber can get swept away in floodwaters. A boat could end up in someone’s living room.

Much of this destruction introduces debris into coastal waterways and wetlands. This is one of several ways NOAA’s Office of Response and Restoration, through the NOAA Marine Debris Program, becomes involved after hurricanes.

While we can’t prevent hurricanes, we can prepare for them. That means doing everything you can to keep you, your family, and your belongings safe, far ahead of any natural disaster.

No matter the size of the storm, you and your family can take steps to reduce the likelihood of your stuff becoming storm debris. It is difficult to prevent buildings or large boats from becoming debris, especially during a large storm, but smaller items be safely stored or secured. After all, no one wants their patio umbrella to knock out a neighbor’s window before it ends up swimming with the fishes.

Here are a few ways to help protect yourself and your belongings in case of a hurricane:

  • Create a plan for your family and home [PDF], practice your evacuation route, and stock an emergency supply kit.
  • Secure yard items before a storm. Make a list of items to bring inside in case of hurricane-force winds or flooding. This could be patio furniture, lawn decorations, tools, trash cans, planters, etc.
  • Invest in storm-resilient building designs, which might include raising the level of your house for areas at high risk of flooding or installing a roof that can withstand high winds.
  • Boaters and fishers: Pull vessels and fishing gear out of the water before a storm. If you’re unable to remove the boat from the water, properly secure it [PDF].

A Boat out of Water

Boat half-sunk in Vermilion Bay, Lousiana.

Finding a safe and secure location for boats during a storm proves to be a huge challenge for many along the coasts, which is how a great deal of boats end up like this one after Hurricanes Katrina and Rita. (U.S. Coast. Guard)

Dealing with the large number of abandoned and derelict vessels after a storm is often a complicated and expensive ordeal. As a result, we should try to keep boats from ending up in this sorry state in the first place. Unfortunately, finding a safe and secure location for boats during a storm proves to be a huge challenge for many along the coasts.

A few areas do show promise in creating safe spaces for vessels during storms. One example is the Clean and Resilient Marina Initiative from the Gulf of Mexico Alliance, a regional partnership made up of the Gulf states. According to the alliance, “This improved program…provides additional recommendations to strengthen local marinas’ ability to withstand natural and man-made disasters.”

The initiative offers best management practices [PDF] for incorporating resilience and environmental responsibility into everything from the design and siting of marinas to strategies for evacuating them during a disaster.

Another example is the concept of “harbors of refuge,” which several organizations in Louisiana are looking to implement on public lands along the coast. A harbor of safe refuge is “a port, inlet, or other body of water normally sheltered from heavy seas by land and in which a vessel can navigate and safely moor.”

Providing resilient infrastructure able to withstand high winds and waters helps better protect boats, and offering these facilities on public lands creates opportunities for public funding to help pay for the upgrades or for salvage after a storm.

Taking on Disasters

The NOAA Marine Debris Program (MDP) is also taking a proactive approach to planning for disasters.

Cover of Alabama Incident Waterway Debris Response Plan, with damaged boats.

The NOAA Marine Debris Program worked with the State of Alabama to release the first in a series of comprehensive plans to help coastal states better prepare for an acute waterway debris release, such as in a hurricane. (NOAA)

In 2012, Congress expanded the program’s responsibilities to include “severe marine debris events,” which formalized their role in preparing for and responding to disaster debris.

This was in the wake of the 2011 Japan earthquake and tsunami, and states were struggling to deal with the tsunami debris—from small boats to massive docks—washing up on U.S. shores. Furthermore, the massive storm known as Sandy had recently hit the East Coast, leaving its own path of destruction along coastal waterways.

As a result, the NOAA MDP has started a proactive planning program for dealing with these types of large, disaster-related debris events. They began by working with the State of Alabama to develop a waterway debris emergency response plan and will now move on to work with other coastal states.

This effort includes both a comprehensive plan and field action guide which spells out information such as which agencies have authorities to remove disaster-related debris if it lands in a given waterway, as well as points of contact at those agencies. The plan is meant to be a broad, useful tool both for the NOAA MDP and the state in case of a natural disaster producing large amounts of debris.

To learn more about how you can prepare for hurricanes, visit NOAA’s National Hurricane Center at, and read more about the NOAA Marine Debris Program’s efforts at


How Beach Cleanups Help Keep Microplastics out of the Garbage Patches

Basket full of faded, old plastic bottles on a beach.

Cleaning up a few plastic bottles on a beach can make a big difference when it comes to keeping microplastics from entering the ocean. (NOAA)

These days plastic seems to be everywhere; unfortunately, that includes many parts of the ocean, from the garbage patches to Arctic sea ice. With this pollution increasingly in the form of tiny plastic bits, picking up a few bottles left on the beach can feel far removed from the massive problem of miniscule plastics floating out at sea.

However, these two issues are more closely connected than you may think.

But how do we get from a large plastic water bottle, blown out of an overfilled trash can on a beach, to innumerable plastic pieces no bigger than a sesame seed—and known as microplastics—suspended a few inches below the ocean surface thousands of miles from land?

The answer starts with the sun and an understanding of how plastic deteriorates in the environment.

The Science of Creating Microplastics

Plastic starts breaking down, or degrading, when exposed to light and high temperatures from the sun. Ultraviolet B radiation (UVB), the same part of the light spectrum that can cause sunburns and skin cancer, starts this process for plastics.

This process, known as photo-oxidation, is a chemical reaction that uses oxygen to break the links in the molecular chains that make up plastic. It also happens much faster on land than in the comparatively cool waters of the ocean.

For example, a hot day at the beach can heat the sandy surface—and plastic trash sitting on it—up to 104 degrees Fahrenheit. The ocean, on the other hand, gets darker and colder the deeper you go, and the average temperatures at its surface in July can range from 45 degrees Fahrenheit near Adak Island, Alaska, to 89 degrees in Cannon Bay, Florida.

Back on that sunny, warm beach, a plastic water bottle starts to show the effects of photo-oxidation. Its surface becomes brittle and tiny cracks start forming. Those larger shards of plastic break apart into smaller and smaller pieces, but they keep roughly the same molecular structure, locked into hydrogen and carbon chains. A brisk wind or child playing on the beach may cause this brittle outer layer of plastic to crumble. The tide washes these now tiny plastics into the ocean.

Once in the ocean, the process of degrading slows down for the remains of this plastic bottle. It can sink below the water surface, where less light and heat penetrate and less oxygen is available. In addition, plastics can quickly become covered in a thin film of marine life, which further blocks light from reaching the plastic and breaking it down.

An Incredible Journey

Lots of tiny pieces of plastic covering rocks.

Microplastics, tiny bits of plastic measuring 5 millimeters or less, are often the result of larger pieces of plastic breaking down on land before making it into the ocean. They can also come from cosmetics and fleece clothing. (NOAA)

In general, plastic breaks down much, much more slowly in the ocean than on land. That means plastic objects that reach the ocean either directly from a boat (say trash or nets from a fishing vessel) or washed into the sea before much degradation has happened are much less likely to break into smaller pieces that become microplastics. This also applies to plastics that sink below the ocean surface into the water column or seafloor.

Instead, plastic that has spent time heating up and breaking down on land is most likely to produce the microplastics eventually accumulating in ocean gyres or garbage patches, a conclusion supported by the research of North Carolina State University professor Anthony Andrady and others.

Of course, microplastics in the form of “microbeads” in face wash and other cosmetics or microfibers in fleece clothing also can reach the ocean by slipping through waste water treatment systems.

However, regularly patrolling your favorite beach or waterway and cleaning up any plastic or other marine debris can go a long way to keeping millions of tiny microplastics—some so tiny they can only be seen with a microscope—from reaching the garbage patches and other areas of the ocean.

The great thing is anyone can do this and you don’t have to wait for the International Coastal Cleanup each September to get started.

Find more tips and resources to help you on your way:


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