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From the Florida Keys to Australia’s Great Barrier Reef, pockets of oceans, bays, and estuaries around the world are designated as marine protected areas (MPAs). In the United States alone, there are about 1,700 MPAs—nearly 41% of the nation’s marine waters.

Governments establish MPAs to help protect marine ecosystems that are threatened by human activity, such as overfishing or petroleum drilling. An MPA may also be established to protect underwater archaeological sites, shipwrecks, and other historically important places. For example, the Thunder Bay Marine Sanctuary was created in 2000 to protect shipwrecks in the Great Lakes.

An MPA may be defined by a range of rules. Restrictive MPAs might prohibit any human activity in the area. Others might simply establish limits on how many fish can be caught or what kind diving or boating can take place. The ways MPAs are managed vary quite a bit depending on the unique features of that area.

Establishing a marine protected area can help both marine ecosystems and local communities. For example, protecting mangrove forests and coral reefs along a coastline can provide healthy habitats for marine life, and they also strengthen the shoreline against erosion. Scientists who studied the impact of a tsunami in the Indian Ocean in 2004 found that thriving mangrove fringes and other coastal ecosystems reduced the tidal wave’s damage to coastal human communities. MPAs can also help local economies by promoting tourism and responsible fishing practices. MPAs also provide scientists with living labs in which to study marine ecosystems and other features of the sea.

By observing marine protected areas, researchers can learn how to better manage other threatened regions that are not protected. Designating an area as an MPA is also one way to preserve and promote biodiversity, which makes ecosystems healthier.

Governments rely on oceanographic research in order to know what marine areas deserve protection. National Geographic Explorer Pelayo Salinas-de-León researched marine ecosystems around Isla Darwin and Isla Wolf of the Galápagos. Much of his research has focused on the role of marine protected areas. Government officials in Ecuador used his research in deciding to designate about 40,000 square kilometers (15,444 square miles) near the islands as a no-take marine sanctuary. That means there is no commercial or recreational fishing or collection of wildlife from the area.

Despite the benefits of MPAs, they are limited in their ability to protect marine ecosystems and other sea resources. Only about one percent of the world’s oceans are protected. In many cases, MPAs are not effectively managed. The areas are also under pressure from commercial fishing interests and others who want to use the waters in ways that violate MPA rules. Raising awareness of the long-term benefits of marine protection may help ease tensions and improve MPA management in the future.