Water Depth, Depth Of Water
noun
The water deepness is the water depth. You should check this before diving into the water so you don't hit your face.
すいしん
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
ここは水深100フィートです。
It's one hundred feet deep here.
この川の水深は十メートルです。
The depth of this river is ten meters.
水深が浅いプールで泳ぐのが好きです。
I like swimming in a shallow pool.