Ocean Trench
noun
An ocean gutter is an ocean trench.
かいこう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
鰻がフィリピン海溝の近くで産卵することは、フィリピン人に知られているのでしょうか。
I wonder if Filipinos know that the spawning place for eels is close to the Philippine Trench.