Charles Ellicott Commentary Job 36:30

"Behold, he spreadeth his light around him; And he covereth the bottom of the sea." — Job 36:30 (ASV)

His light appears to mean here the lightning which flashes forth from the cloud.

And covers the bottom of the sea. —Literally, it has covered the roots of the sea: i.e., it, the lightning, or He, God, has covered those clouds which are composed of the roots of the sea, that is, the drops of water which are exhaled from the sea.