Submarine
noun
A conceal in the water warship is a submarine.
せんすいかん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
多分あの潜水艦の中で片方のイヤリングを失くしてしまったの。
I probably lost my other earring while I was on the submarine.