Job 7:12 - Ellicott's Commentary On The Whole Bible

Am I a sea, or a whale...? — This very hard verse it seems most reasonable to explain, if we can, from Scripture itself: e.g., in Jeremiah 5:22 we read, “Fear ye not me? saith the Lord: will ye not tremble at my presence, which have placed the sand for the bound of the sea?" The writer was probably familiar with Egypt when the Nile, which is still called the sea, was carefully watched and guarded by dykes that its overflow might not destroy the land. So Job exclaims, “Am I like the sea, or one of its monsters — like that Leviathan which Thou hast made to take his pastime therein, that Thou keepest guard over me and makest me thy prisoner continually, shutting me up on every side so fast in prison that I cannot get free?”