Milwaukee Deep

During the Five Deeps Expedition, explorer Victor Vescovo achieved the first crewed descent to the location on 21 December 2018.

[3] It is named for the USS Milwaukee, which recorded the first echo soundings of the Puerto Rico Trench in 1939,[8] and was itself named for the city of Milwaukee.Located roughly 76.0 miles (122.3 km; 66.0 nmi) north of the coast of the main island of Puerto Rico at Punto Palmas Altas in Manatí,[9][10] the maximum depth of the Milwaukee Deep is 8,376 metres (27,480 ft; 4,580 fathoms), as directly measured by Vescovo during his 2018 descent to the deepest point of the Atlantic Ocean.

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 22,950 feet (7,000 m; 3,825 fathoms) at (26°32′N 60°06′W / 26.533°N 60.100°W / 26.533; -60.100).

[11] In 1964, the French submersible Archimède explored the Puerto Rico Trench to a depth of approximately 8,300 m (27,200 ft; 4,500 fathoms) but did not reach its deepest point.

[3] On 21 December 2018 Victor Vescovo made the first crewed descent to the deepest point of the trench in the Deep-Submergence Vehicle DSV Limiting Factor (a Triton 36000/2 model submersible) and measured a depth of 8,376 m (27,480 ft; 4,580 fathoms) by direct CTD pressure measurements.

Location of the Puerto Rico Trench, USGS
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.
Discoverer ship USS Milwaukee (CL-5)
Deep Submersible Support Vessel DSSV Pressure Drop and DSV Limiting Factor at its stern