Marianas Trench Marine
The Marianas Trench Marine National Monument is a United States National Monument that consists of 95,216 square miles (60,938,240 acres) of submerged lands and waters of the Mariana Archipelago. It includes the Islands Unit - the waters and submerged lands of the three northernmost Mariana Islands (Farallon de Pajaros or Uracas, Maug, and Asuncion); the Volcanic Unit (Vents Unit) - the submerged lands within 1 nautical mile of 21 designated volcanic sites; and the Trench Unit - the submerged lands extending from the northern limit of the Exclusive Economic Zone of the United States in the Commonwealth of the Northern Mariana Islands to the southern limit of the Exclusive Economic Zone of the United States in the Territory of Guam.
In the Islands Unit, unique reef habitats support marine biological communities dependent on basalt rock foundations, unlike those throughout the remainder of the Pacific. These reefs and waters are among the most biologically diverse in the Western Pacific and include the greatest diversity of seamount and hydrothermal vent life yet discovered. They also contain one of the most diverse collections of stony corals in the Western Pacific, including more than 300 species, higher than any other U.S. reef area. The submerged caldera at Maug is one of only a few known places in the world where photosynthetic and chemosynthetic communities of life coexist. The caldera is some 1.5 miles wide and 820 feet deep, an unusual depth for lagoons. The lava dome in the center of the crater rises to within 65 feet of the surface. Hydrothermal vents at about 475 feet in depth along the northeast side of the dome spew acidic water at scalding temperatures near the coral reef that quickly ascends to the sea surface. Thus, coral reefs and microbial mats are spared much of the impact of these plumes and are growing nearby, complete with thriving tropical fish. As ocean acidification increases across the Earth, this caldera offers scientists an opportunity to look into the future and ensure continuation of coral reef communities.
The Volcanic Unit (Vents Unit) - an arc of more than 20 undersea mud volcanoes and thermal vents - supports unusual life forms in some of the harshest conditions imaginable. Here species survive in the midst of hydrothermal vents that produce highly acidic boiling water.