Milwaukee Deep, also known as the Milwaukee Depth, is the deepest part of the Puerto Rico Trench, constituting the deepest points in the Atlantic Ocean. Together with the surrounding seabed area, known as Brownson Deep, the Milwaukee Deep forms an elongated depression that constitutes the floor of the trench. As there is no geomorphological distinction between the two, it has been proposed that the use of both names to refer to distinct areas should be reviewed.
During the Five Deeps Expedition, explorer Victor Vescovo achieved the first crewed descent to the location on 21 December 2018. while the name Milwaukee Deep was used by others. However, likely due to the factors mentioned above, the expedition has not used any particular name to refer to the site of their Atlantic dive. It is named for the USS Milwaukee, which recorded the first echo soundings of the Puerto Rico Trench in 1939, and was itself named for the city of Milwaukee.thumb|right|300px|Location of the Puerto Rico Trench, [[United States Geological Survey|USGS]]Located roughly north of the coast of the main island of Puerto Rico at Punto Palmas Altas in Manatí, the maximum depth of the Milwaukee Deep is , as directly measured by Vescovo during his 2018 descent to the deepest point of the Atlantic Ocean. in 1954 by John Lyman, professor of oceanography at University of North Carolina at Chapel Hill, and in 2019 and in 2021.thumb|right|300px|Perspective view of the sea floor of the [[Atlantic Ocean and the Caribbean Sea. The Lesser Antilles are on the lower left side of the view and Florida is on the upper right. The purple sea floor at the center of the view is the Puerto Rico Trench, the deepest part of the Atlantic Ocean.]]
History
thumb|right|300px|Discoverer ship
The ocean floor feature is named for the USS Milwaukee (CL-5), a U.S. Navy Omaha class cruiser, which discovered the Milwaukee Deep on February 14, 1939 with a reading of . On August 19, 1952, the U.S. Fish and Wildlife vessel Theodore N. Gill obtained a reading of at (), virtually identical with the Milwaukees reading. By then, the existence of deep water to the Atlantic Ocean side of the Caribbean had been known for more than a century.
One of the area's earliest soundings was obtained June 12, 1852 by Lt. S. P. Lee, U.S. Navy brig Dolphin, with a reading of at ().
See also
- List of submarine topographical features
- Oceanic trench
- Challenger Deep