Oceanus was a divine figure in classical antiquity, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world. According to Homer, Oceanus was the ocean-stream at the margin of the habitable world, the father of everything, limiting it from the underworld and flowing around the Elysium. Hence Odysseus has to traverse it in order to arrive in the reign of the dead. In the lliad, Hera mentions her intended journey to her foster parents, namely "Oceanus, from whom they all are sprung".
εἶμι γὰρ ὀψομένη πολυφόρβου πείρατα γαίης,Ὠκεανόν τε θεῶν γένεσιν καὶ μητέρα Τηθύν,οἵ μ' ἐν σφοῖσι δόμοισιν ἐὺ τρέφον ἠδ' ἀτίταλλονδεξάμενοι Ῥείας [...]
(For i am fairing to visit the limits of the all-nurturing earth, and Oceanus, from whom the gods are sprung, and mother Tethys, even them that lovingly nursed and cherished me in their halls, when they had taken me from Rhea [...])
Helios rises from the deep-flowing Oceanus in the east and at the end of the day sinks back into the Oceanus in the west. Also the other stars "bathe [...] in the stream of Ocean". Oceanus is called βαθύρροος ("deep-flowing") and ἀψόρροος ("flowing back to itself, circular"), the latter quality being reflected in its depiction on the shield of Achilles.
Ἐν δ' ἐτίθει ποταμοῖο μέγα σθένος Ὠκεανοῖοἄντυγα πὰρ πυμάτην σάκεος πύκα ποιητοῖο.
(Therein he set also the great might of the river Oceanus, around the uttermost rim of the strongly-wrought shield.) In Greek mythology, this ocean-stream was personified as a Titan, the eldest son of Uranus and Gaia. Oceanus' consort is his sister Tethys, and from their union came the ocean nymphs, also referred to as the three-thousand Oceanids, and all the rivers of the world, fountains, and lakes.
In most variations of the war between the Titans and the Olympians, or Titanomachy, Oceanus, along with Prometheus and Themis, did not take the side of his fellow Titans against the Olympians, but instead withdrew from the conflict. In most variations of this myth, Oceanus also refused to side with Cronus in the latter's revolt against their father, Uranus. He is, it appears, some sort of an outlaw to the society of Gods, as he also does not - and unlike all the other river gods, his sons - take part in the convention of gods on Mount Olympus. Besides, Oceanus appears as a representative of the archaic world that Heracles constantly threatened and bested. As such, the Suda identifies Oceanus and Tethys as the parents of the two Kerkopes, whom Heracles also bested. Heracles forced Helios to lend him his golden bowl, in order to cross the wide expanse of the Ocean on his trip to the Hesperides. When Oceanus tossed the bowl about, Heracles threatened him and stilled his waves. The journey of Heracles in the sun-bowl upon Oceanus became a favored theme among painters of Attic pottery
