Oceanus refers to the ocean  which the Greeks and Roman thought of as life circling the world. Strictly speaking, it was the ocean-stream at the middle of earth in which floated the habitable hemisphere. In Greek mythology this world-ocean was personified as a Titan, a son of Uranus and Gaia. In ancient Greek beliefs this Titan is often described as having the upper body of a muscular man with a long beard and the lower body of a serpent.