海かい淵えん

noun

ocean deep; deepest part of a trench

Technical oceanographic term for the deepest zone of the ocean, especially the floor of a deep-sea trench.

• マリアナ海かい溝こうの海かい淵えんは、地ち球きゅう上じょうで最もっとも深ふかい場ば所しょの一ひとつだ。

  The deepest part of the Mariana Trench is one of the deepest places on Earth.