Even if you live far from the coast, the ocean affects you. It impacts the entire planet. The ocean makes up over 70% of Earth’s surface and contains 97% of the water on Earth. It provides over half of the oxygen on Earth. It also regulates the climate and absorbs about 30% of the carbon dioxide released into the atmosphere, including human-produced carbon dioxide that causes climate change.

The ocean is a haven for life. The ocean also holds cultural significance to people around the world both today and throughout history. Many cultures, such as native Hawaiian culture, recognize the ocean as the source of life in their creation stories. Scientists agree that life likely began in the ocean over 3.5 billion years ago. It is home to at least 250,000 species and possibly millions more species yet to be discovered. The ocean also provides food for three billion people worldwide and income to millions through fishing, recreation, transportation and other economic activities.

But the ocean is under threat. Climate change (from human activities that produce greenhouse gases), pollution and overfishing are the most significant threats to the ocean and the life within it. Coastal communities, small island states and historically under-resourced communities are more vulnerable to these threats and bear more of the costs of polluting and exploiting the ocean.

One tool to protect the ocean from these threats is marine protected areas (MPAs). An MPA is a region of the ocean where marine environments receive some degree of protection from human activity. The International Union for Conservation of Nature (IUCN) defines an MPA as, “a clearly defined geographical space, recognized, dedicated, and managed … to achieve the long-term conservation of nature with associated ecosystem services and cultural values.” Governments also provide their own legal definitions and associated goals for MPAs. Generally, these include protecting ecosystems and cultural heritage within a particular marine area.

MPAs are considered an area-based conservation measure because they establish protections for a particular physical space. While MPAs help protect the geography itself, they also protect the species that live there and the site’s cultural heritage.

Around the world, there are over 16,000 MPAs covering 35 million square kilometers (13.5 million square miles) of ocean. That equates to over 9.6% of the world’s ocean. In recent years, some nations have been able to establish very large MPAs covering 100,000 square kilometers (3,800 square miles). Some countries, such as the Cook Islands, have turned their entire national waters into an MPA.

MPA Goals and Benefits

For centuries, and possibly millennia, Indigenous people have protected and managed marine resources, balancing fishing and other human needs with ecosystem preservation. But modern technology has made it possible to fish in places that were once unreachable and catch fish more efficiently, leading to overfishing or fishing beyond what can be replaced sustainably. Other factors that contribute to overfishing include the global increase in the demand for seafood, government subsidies that encourage overfishing, ineffective regulation or enforcement and illegal fishing. Fishing can also cause harm to marine environments when fishers catch the species they hadn’t intended to or destroy habitats through practices like bottom trawling, which involves dragging a large net along the ocean floor. Mining and oil extraction are other activities that harm marine ecosystem. The overexploitation of marine resources has created a global need to protect marine habitats and establish more sustainable use of marine resources.

MPAs offer ecosystems a reprieve from human activities and protect an area’s biodiversity. Although MPAs often restrict or carefully manage fishing, they can be beneficial to fishing by allowing fish populations to grow and reproduce, replenishing fish stocks. Areas that allow carefully managed fishing typically prohibit the kind of large-scale, industrial fishing that enables well-resourced nations to drain aquatic resources from less wealthy communities. This, in turn, can help small-scale fishers whose livelihoods depend on fishing and communities who depend on seafood for nutrition.

MPAs provide significant cultural benefits as well. For fishing and seafaring cultures, this means preserving an ancestral way of living. In some cultures, the ocean or local marine environment holds spiritual significance. There is also some evidence to suggest that MPAs promote community resilience by preserving the ocean’s ability to absorb carbon, which helps protect against climate change, and providing economic value through tourism.

MPAs also provide a unique opportunity for marine scientists to study undisturbed ecosystems, free from human interference. They can also provide key insights into how marine ecosystems recover from the effects of climate change and overfishing.

Types of MPAs

While many MPAs share similar goals, they vary in focus and the level of protection provided. There are two main ways to categorize MPAs by level of protection. Protected Planet’s MPA Guide ranks MPAs on a spectrum of protection: minimally protected, lightly protected, highly protected and fully protected.

The second way to categorize MPAs is the IUCN’s categories for protected areas, though these classifications were originally developed for land conservation.

Strict nature reserves and wilderness areas are usually no-take MPAs, meaning that people are not allowed to take any resources. Activities that aren’t allowed include fishing and mining. Other activities, such as swimming and boating, may be permitted.

National parks are large areas preserved in their natural state as public property. They are designed to protect the natural and cultural aspects of the area and wildlife within the park.

National monuments or features often protect a specific geological formation, such as a cave or seamount. These areas typically allow visitors.

A habitat or species management area conserves, protects and supports a particular species and their habitat.

A protected seascape is a flexible category that allows more human activity and interaction with nature, including tourism. These areas are typically guided by a conservation plan.

Protected areas with sustainable use of natural resources allow some additional level of human use, including small-scale fishing, while still implementing management measures to reduce harm to the environment.

Scientists have found that even MPAs that allow fishing and other human activities still provide some level of effective protection to species and habitats. However, the most effective MPAs tend to have five features: no fishing, good enforcement, established for at least 10 years, area of over 100 square kilometers (39 square miles) and isolation.

An MPA that meets this criteria is Papahānaumokuākea Marine National Monument in Hawai‘i. Designated as an MPA in 2006, it is over 1.5 million square kilometers (0.6 million square miles), making it one of the largest MPAs on Earth. The area includes coral reefs that support wildlife not found anywhere else and endangered species, including the Laysan duck (Anas laysanensis). Papahānaumokuākea is also a site of deep cultural and spiritual significance to native Hawaiians. It is named after Hawaiian ancestors, Papahānaumoku and Wākea, believed to have created the Hawaiian Islands and people. The continued success of the MPA is due to its strict enforcement and financial support.

Are MPAs Effective? What Are the Challenges?

In 2022, 196 nations adopted the Kunming-Montreal Global Biodiversity Framework, pledging to protect 30% of the ocean by 2030, also referred to as the 30x30 goal. While there has been an increase in the area of ocean protected, less than 10% of oceans were designated as MPAs as of 2026. In part, this is because there are particular challenges and complexities that face the creation of MPAs and protecting marine ecosystems broadly.

MPAs around the world differ in the level of protection and support for a particular ocean area at the international, federal, state and local levels. Importantly, MPAs are not solely run by governments; instead, the work and collaboration of nonprofits, governments and community members make MPAs possible. At best, this can lead to meaningful cooperation and lasting change. However, there are challenges from involving many groups and stakeholder needs.

Marine ecosystems often span national boundaries. Sometimes they are beyond any single nation’s jurisdiction in an area known as the High Seas. This presents a special challenge for establishing and maintaining MPAs and requires international collaboration. Because of these challenges, there are relatively few MPAs in the High Seas—only about 1% of the High Seas is protected as MPAs.

While establishing no-take zones can help ecosystems recover, they are not practical or ethical to implement everywhere. This includes places where artisanal fishing is part of the area’s cultural heritage or where seafood provides a substantial source of food.

Additionally, it is important to remember that, while MPAs can provide long-term economic benefits, there can also be short-term economic costs. Local stakeholders should be made aware of this and steps should be taken to mitigate these costs. For example, Tubbataha Reefs Natural Park in the Philippines set up fees for divers to offset the financial costs of conservation.

Some question the quality of protections offered by MPAs, especially those that still allow some harmful practices, including bottom trawling. For example, though 41% of U.S. waters are MPAs, only 3% of U.S. MPAs are considered no-take zones.

Recent studies suggest that MPAs may extend benefits, like protecting important feeding and breeding grounds, to highly migratory species. But other studies indicate that the benefit might be minimal. Some advocates, including members of the fishing industry, question just how much no-take MPAs support sustainable fishing, stating that fishers will simply pursue more aggressive operations elsewhere in the ocean.

On the other hand, studies using satellite data have confirmed that the world’s most strongly protected MPAs deter illegal industrial fishing. In one such study conducted by the Nature Conservancy, National Geographic Pristine Seas and the University of California Santa Barbara, researchers tracked fishing vessels using the onboard locating system known as the Automatic Identification System (AIS). They examined satellite imaging alongside location data in 1,380 highly protected MPAs. The data showed little industrial fishing activity in those MPAs, confirming that MPAs with high levels of protection do deter illegal fishing.

Ultimately, MPAs and sustainable fisheries management cannot replace one another; they must be used together to best preserve ecosystems and meet people’s needs.

Scientists and resource managers continue to assess the efficacy of MPAs globally. The MPA Guide was established as a framework to measure the effectiveness of MPAs. Specifically, the MPA Guide evaluates the stage of the MPA’s development and the level of protection provided to the ecosystem. Further investment in oceans would also continue to help marine conservation. Of all the UN’s Sustainable Development Goals, SDG-14, “Life Below Water,” is the most underfunded. Protecting oceans requires extensive funding, but these funds must be distributed to support the nations that need them the most.

People Provide Protection

People can act to ensure the protection of marine habitats. Scientists and policymakers play a more visible role in the process, but local advocates and community members also have a say in creating MPAs.

Community involvement and local culture is critical to the success of marine protection. Successful approaches used for marine conservation consider local context and cultural norms. Indigenous and local communities have irreplaceable knowledge from living alongside their coasts, and that is why it is imperative that they are directly involved in the development of marine protections.

In the Philippines, a major coral reef near Panaon Island was designated a protected seascape after locals used a cultural festival to pressure lawmakers to protect the area. Cabo Pulmo National Park at the tip of Baja California in Mexico is another example of locals advocating for environmental protection. In the 1990s, a family of fishers gained the support of their government and community to designate the area as a national park and recover the area’s biodiversity. As one of the “Islands and Protected Areas of the Gulf of California,” the park was designated a UNESCO World Heritage Site in 2005.

These marine protection wins can happen on a large scale as well.

National Geographic Pristine Seas is an example of marine protection that involves a wide breadth of people, from filmmakers to scientists to policy experts. The effort involves local partners, Indigenous peoples and government officials to protect many critical ocean habitats across the globe. Pristine Seas has established 30 of the largest MPAs totaling 6.9 million square kilometers (2.6 million square miles), hosted 45 expeditions and contributed to over 300 peer-reviewed studies.

National Geographic Explorer in Residence and ocean advocate Enric Sala started this project in 2008. To Sala, seeing is believing. He believes that building a connection between people and the ocean leads to tangible progress in marine protection.

“When you take people into the field, they invariably fall in love with the ocean,” Sala told National Geographic Society. “If you want people to protect the ocean you must, of course, show them the scientific data. But first you must touch their hearts.”

Sala not only exposes critical marine conservation work to the public, but he also actively contributes his expertise to help find a path toward achieving the ambitious 30x30 goal. Like other ocean advocates, Sala sees the power of MPAs for people and ecosystems. Inspired by the progress made by Pristine Seas, he plans to keep the momentum.

When thinking of his work with Pristine Seas, Sala says, “It is amazing what we’ve done, but we need more. Much, much more.”