Marine protected areas (MPAs) in the United States serve many different purposes and are established for a variety of reasons. MPAs may include national marine sanctuaries, fishery management zones, national seashores, national parks, national monuments, critical habitats, national wildlife refuges, national estuarine research reserves, state conservation areas, state reserves, and others. These MPAs come in different shapes and sizes, have varying management characteristics, and have been established for a variety of purposes.

http://www.mpa.gov/