A great research documentary on the extreme depths of the Mariana Trench and the mind blowing unseen sea creatures. Very well narrated documentary by David Attenborough. The Mariana Trench or Marianas Trench is located in the western Pacific Ocean about 200 kilometers east of the Mariana Islands; it is the deepest oceanic trench on earth. The maximum known depth of Marian Trench is 10,984 meters however, some unrepeated measurements place the deepest portion at 11,034 meters.