Milwaukee Deep Milwaukee Deep Milwaukee Deep, also known as The Milwaukee Depth, () is the deepest part of the Atlantic Ocean and is part of the Puerto Rico Trench. It has a maximum depth of at least . It is just north of the coast of Puerto Rico at "Punto Palmas Altas" in Manatí. This 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
Sirena Deep Philippine legends of the sirenas, which are a mix of mermaids and sirens. The new name will now appear on geologic and bathymetric maps. Sirena Deep The Sirena Deep was discovered in 1997 by a team of scientists from Hawaii. Its depth (10,732 metres) is thought to be second or third only to the Challenger Deep and possibly Horizon Deep, currently the deepest known places in the ocean. It lies along the Mariana Trench, 200 kilometers to the east of the Challenger Deep and 145 km south of Guam. The Sirena Deep was most probably formed, not through transform fault