海かい底てい炭たん田でん

noun

submarine coal field

Technical term for a coal deposit located under the seabed.

• この地ち域いきの海かい底てい炭たん田でんは、まだ十じゅう分ぶんに調ちょう査さされていない。

  The submarine coal fields in this area have not yet been fully surveyed.