On January 6, 2009, President George W. Bush established the Marianas Trench Marine National Monument by Presidential Proclamation under the authority of the Antiquities Act of 1906. The monument incorporates approximately 95,216 square miles within three units in the Mariana Archipelago. The Mariana Trench Unit is almost 1,100 miles long and 44 miles wide and includes only the submerged lands. The Volcanic Unit consists of small circles (2.3 miles in diameter) around 21 undersea mud volcanoes and thermal vents along the Mariana Arc, again only the submerged lands. The Islands Unit includes only the waters and submerged lands of the three northernmost Mariana Islands, Farallon de Pajaros or Uracas, Maug, and Asuncion, below the mean low water line.
On January 16, 2009, the Secretary of the Interior delegated his management responsibilities for the monument to the Fish and Wildlife Service through Secretary's Order 3284. The Secretary's Order also placed two of the units (the Mariana Trench and Volcanic Units) within the National Wildlife Refuge System as the Mariana Trench and Mariana Arc of Fire National WIldlife Refuges.