The Papahānaumokuākea Marine National Monument (PMNM) is a World Heritage listed U.S. National Monument encompassing 583,000 square miles (1,510,000 km2) of ocean waters, including ten islands and atolls of the Northwestern Hawaiian Islands. It was created in June 2006 with 140,000 square miles (360,000 km2) and expanded in August 2016 by moving its border to the limit of the exclusive economic zone, making it one of the world's largest protected areas. It is internationally known for its cultural and natural values as follows: The area has deep cosmological and traditional significance for living Native Hawaiian culture, as an ancestral environment, as an embodiment of the Hawaiian concept of kinship between people and the natural world, and as the place where it is believed that life originates and to where the spirits return after death. On two of the islands, Nihoa and Mokumanamana, there are archaeological remains relating to pre-European settlement and use. Much of the monument is made up of pelagic and deepwater habitats, with notable features such as seamounts and submerged banks, extensive coral reefs and lagoons.

In the United States, a national monument is a protected area that can be created from any land owned or controlled by the federal government by proclamation of the president of the United States or an act of Congress. National monuments protect a wide variety of natural and historic resources, including sites of geologic, marine, archaeological, and cultural importance. In contrast, national parks in the U.S. must be created by Congressional legislation. Some national monuments were first created by presidential action and later designated as national parks by congressional approval.