Take advantage of the search to browse through the World Heritage Centre information.

Marianas Trench Marine National Monument

Date of Submission: 12/04/2017
Criteria: (viii)(ix)(x)
Category: Natural
Submitted by:
United States Department of the Interior
State, Province or Region:
Pacific Islands, Commonwealth of the Northern Marianas Islands
Ref.: 6238

The Tentative Lists of States Parties are published by the World Heritage Centre at its website and/or in working documents in order to ensure transparency, access to information and to facilitate harmonization of Tentative Lists at regional and thematic levels.

The sole responsibility for the content of each Tentative List lies with the State Party concerned. The publication of the Tentative Lists does not imply the expression of any opinion whatsoever of the World Heritage Committee or of the World Heritage Centre or of the Secretariat of UNESCO concerning the legal status of any country, territory, city or area or of its boundaries.

Property names are listed in the language in which they have been submitted by the State Party


The Marianas Trench Marine National Monument consists of three units : the Trench Unit, encompassing the submerged lands within the Mariana Trench ; the Volcanic Unit, encompassing 21 designated volcanic features and the surrounding submerged lands out to a radius of 1 nautical mile (nm) ; and the Islands Unit, encompassing the waters and submerged lands of the three northernmost Mariana Islands (Farallon de Pajaros, Maug, and Asuncion) from the mean low water line out approximately 50 nautical miles.  The Marianas Trench is approximately 940 nautical miles long and 38 nautical miles wide. Important bottom habitats are protected in the Volcanic and Trench Units, and the Government of the Commonwealth of the Northern Mariana Islands (CNMI) maintains all authority for managing the three islands within the Islands Unit above the mean low water line. The Monument encompasses approximately 24 million hectares of submerged lands and waters of the Marianas Archipelago.  It is managed by the National Oceanic and Atmospheric Administration, the U.S. Fish and Wildlife Service, and the Commonwealth of the Northern Marianas Islands (CNMI), a U.S. territory. 

Islands Unit         55 Q    280259    2272891
Trench Unit         55 P    236676    1334948
Volcanic Unit       55 Q   366692    1974177

Justification of Outstanding Universal Value

The Mariana Trench Marine National Monument is like no other place on Earth in its undersea remoteness.  More people have walked on the moon than descended to the depths of the Mariana Trench.  The site includes the second deepest place on Earth (Sirena Deep) and is immediately adjacent to the deepest place on the planet (Challenger Deep).  The Monument lies at the junction of two tectonic plates, and includes rare geologic features, such as mud volcanoes, submarine volcanoes and hydrothermal vents spewing carbon dioxide. The diverse habitats of the Monument support thriving marine ecosystems, including many newly discovered species.  This description focuses on natural heritage values, but the site also has important cultural heritage values that may be included in a future nomination.

Criterion (viii):  The Marianas Trench is the deepest part of the world’s ocean.  The Marine National Monument includes the second deepest point on Earth, the Sirena Deep, which lies at approximately 35,000 ft deep (10.67 km), more than one mile deeper than Mount Everest is high.  (The world’s deepest spot, the Challenger Deep, lies just outside the Monument boundary.)  The Monument includes some extremely rare features, including the largest mud volcanoes on Earth, 21 submarine volcanoes (a few of which are known to emit nearly pure liquid CO2 and sulfur), and
sites where photosynthetic and chemosynthetic communities co-exist.

The Mariana Trench marks the boundary where the Pacific Plate – the oldest ocean floor on Earth – is being subducted beneath the younger Mariana Plate. Ongoing plate tectonics and seismic activity are creating unparalleled geologic processes, such as massive submarine mud volcanoes and spectacular hydrothermal vents referred to as “smokers,” spewing carbon dioxide bubbles.  This is one of the few sites in the world where chemosynthesis and photosynthesis occur in the same proximity, thereby providing a natural, in-situ laboratory for climate change and ocean acidification research.  Just above the sea floor lie the Monument waters surrounding beautiful Maug caldera and nearby Farallon de Parajos and Asuncion volcanic islands. These islands are in their geologic infancy and exemplify the creation stage of earth’s history. 

Criterion (ix): The Monument includes the waters from the shoreline to 50 nm around the three northernmost islands in the Mariana Archipelago: Farallon de Parajos, Maug, and Asuncion. These remote islands are ringed by coral ecosystems with very high numbers of apex predators, sharks, whales, stony coral, and fish biomass.  They are home to sharks, whales, dolphins, and colorful deep-water fish, along with several species of endangered and threatened populations of sea turtles. The Monument complements the protections of adjacent wildlife conservation reserves on the terrestrial portions of Farallon de Parajos, Maug, and Asuncion islands (protected in perpetuity by the CNMI Government) to protect every link in the evolution of this complex and fragile chain as an integrated ecosystem: birds, predatory fish, corals, seamounts, and the deep sea.

Criterion (x):  The unique geologic features of the Trench and the islands of the Monumentprovide habitat for abundant marine life, including many unusual species.  Recent ocean exploration in the Monument has observed hundreds of different species of animals and dozens of potential new species. New species identified included three cladorhizid sponges, three hexactinellid sponges, a tilefish, a hydromedusae jellyfish, a seastar, and two new species of crinoid.  Many more species are likely to be confirmed at a later date.

Statements of authenticity and/or integrity

The deep sea and coastal ecosystems protected by the Monument are largely intact.  Current threats that could affect the globally significant values of the Monument include climate change impacts already being felt, such as coral bleaching and ocean acidification. Due to the remote location of the Monument and challenge to monitor and enforce unauthorized activities, overfishing, resource damage, ship groundings/abandonment, and invasive species introductions all pose potential ecological threats and resource integrity concerns.

Comparison with other similar properties

The Monument would be the first World Heritage site to include little-explored geological phenomena, including active sites of plate tectonics and underwater volcanic activity.   Numerous expeditions using remotely operated vehicles, and high-tech submarines are in development to continue to learn more about what lies at these mysterious depths that may benefit humanity. The Monument would contribute under-represented and important deep-sea habitats.