Psalm 68:22 The Lord said, I will bring again from Bashan, I will bring my people again from the depths of the sea:

Here again scripture was pointing forward to the Messiah. In him, God did bring his people from out of the sea (kingdom of darkness, the world). Jesus said the following to Peter: Luke 5:10 ..... from henceforth thou shalt catch men.

God used someone to catch us from the sea, he then uses us to free others from the "depths of darkness". When we walk in him, there is no more sea (Rev 21:1) i.e. no more darkness. How you ask? 1 John 1:5 ..... God is light, and in him is no darkness at all.
Be blessed.