'Depths' in the Bible

But whosoever shall offend one of these little ones who believe in me, it were profitable for him that a great millstone had been hanged upon his neck and he be sunk in the depths of the sea.

but God has revealed to us by his Spirit; for the Spirit searches all things, even the depths of God.

But to you I say, the rest who are in Thyatira, as many as have not this doctrine, who have not known the depths of Satan, as they say, I do not cast upon you any other burden;