According to M. L. West, the etymology of Oceanus is "obscure" and "cannot be explained from Greek". The use by Pherecydes of Syros of the form "Ogenos" () for the name lends support for the name being a loanword. However, according to West, no "very convincing" foreign models have been found. A Semitic derivation has been suggested by several scholars, while R. S. P. Beekes has suggested a loanword from the Aegean Pre-Greek non-Indo-Europeansubstrate. Nevertheless, Michael Janda sees possible Indo-European connections.
Passages in a section of the Iliad called the Deception of Zeus, suggest the possibility that Homer knew a tradition in which Oceanus and Tethys (rather than Uranus and Gaia, as in Hesiod) were the primeval parents of the gods. Twice Homer has Hera describe the pair as "Oceanus, from whom the gods are sprung, and mother Tethys". According to M. L. West, these lines suggests a myth in which Oceanus and Tethys are the "first parents of the whole race of gods." However, as Timothy Gantz points out, "mother" could simply refer to the fact that Tethys was Hera's foster mother for a time, as Hera tells us in the lines immediately following, while the reference to Oceanus as the genesis of the gods "might be simply a formulaic epithet indicating the numberless rivers and springs descended from Okeanos" (compare with Iliad21.195-197). But, in a later Iliad passage, Hypnos also describes Oceanus as "genesis for all", which, according to Gantz, is hard to understand as meaning other than that, for Homer, Oceanus was the father of the Titans.
Plato, in his Timaeus, provides a genealogy (probably Orphic) which perhaps reflected an attempt to reconcile this apparent divergence between Homer and Hesiod, in which Uranus and Gaia are the parents of Oceanus and Tethys, and Oceanus and Tethys are the parents of Cronus and Rhea and the other Titans, as well as Phorcys. In his Cratylus, Plato quotes Orpheus as saying that Oceanus and Tethys were "the first to marry", possibly also reflecting an Orphic theogony in which Oceanus and Tethys, rather than Uranus and Gaia, were the primeval parents. Plato's apparent inclusion of Phorcys as a Titan (being the brother of Cronus and Rhea), and the mythographer Apollodorus's inclusion of Dione, the mother of Aphrodite by Zeus, as a thirteenth Titan, suggests an Orphic tradition in which the Titan offspring of Oceanus and Tethys consisted of Hesiod's twelve Titans, with Phorcys and Dione taking the place of Oceanus and Tethys.
When Cronus, the youngest of the Titans, overthrew his father Uranus, thereby becoming the ruler of the cosmos, according to Hesiod, none of the other Titans participated in the attack on Uranus. However according to the mythographer Apollodorus, all the Titans—except Oceanus—attacked Uranus.Proclus, in his commentary on Plato's Timaeus, quotes several lines of a poem (probably Orphic) which has an angry Oceanus brooding aloud as to whether he should join Cronus and the other Titans in the attack on Uranus. And, according to Proclus, Oceanus did not in fact take part in the attack.
Oceanus seemingly also did not join the Titans in the Titanomachy, the great war between the Cronus and his fellow Titans, and Zeus and his fellow Olympians, for control of the cosmos; and following the war, although Cronus and the other Titans were imprisoned, Oceanus certainly seems to have remained free. In Hesiod, Oceanus sends his daughter Styx, with her children Zelus (Envy), Nike (Victory), Cratos (Power), and Bia (Force), to fight on Zeus' side against the Titans, And in the Iliad, Hera says that during the war she was sent to Oceanus and Tethys for safekeeping.
Sometime after the war, Aeschylus' Prometheus Bound, has Oceanus visit his nephew the enchained Prometheus, who is being punished by Zeus for his theft of fire. Oceanus arrives riding a winged steed, saying that he is sympathetic to Prometheus' plight and wishes to help him if he can. But Prometheus mocks Oceanus, asking him: "How did you summon courage to quit the stream that bears your name and the rock-roofed caves you yourself have made" Oceanus advises Prometheus to humble himself before the new ruler Zeus, and so avoid making his situation any worse. But Prometheus replies: "I envy you because you have escaped blame for having dared to share with me in my troubles."
According to Pherecydes, while Heracles was travelling in Helios's golden cup, on his way to Erytheia to fetch the cattle of Geryon, Oceanus challenged Heracles by sending high waves rocking the cup, but Heracles threatened to shoot Oceanus with his bow, and Oceanus in fear stopped.
Although sometimes treated as a person (such as Oceanus visiting Prometheus in Aeschylus' Prometheus Bound, see above) Oceanus is more usually considered to be a place, that is, as the great world-encircling river. Twice Hesiod calls Oceanus "the perfect river" (), and Homer refers to the "stream of the river Oceanus" ( ? ). Both Hesiod and Homer call Oceanus "backflowing" (), since, as the great stream encircles the earth, it flows back into itself. Hesiod also calls Oceanus "deep-swirling" (), while Homer calls him "deep-flowing" ().Homer says that Oceanus "bounds the Earth", and Oceanus was depicted on the shield of Achilles, encircling its rim, and so also on the shield of Heracles.
Both Hesiod and Homer locate Oceanus at the ends of the earth, near Tartarus, in the Theogony, or near Elysium, in the Iliad, and in the Odyssey, has to be crossed in order to reach the "dank house of Hades". And for both Hesiod and Homer, Oceanus seems to have marked a boundary beyond which the cosmos became more fantastical. The Theogony has such fabulous creatures as the Hesperides, with their golden apples, the three-headed giant Geryon, and the snake-haired Gorgons, all residing "beyond glorious Ocean". While Homer located such exotic tribes as the Cimmerians, the Aethiopians, and the Pygmies as living nearby Oceanus.
In Homer, Helios the sun, rises from Oceanus in the east, and at the end of the day sinks back into Oceanus in the west, and the stars bathe in the "stream of Ocean". According to later sources, after setting, Helios sails back along Oceanus during the night from west to east.
Just as Oceanus the god was the father of the river gods, Oceanus the river was said to be the source of all other rivers, and in fact all sources of water, both salt and fresh. According to Homer, from Oceanus "all rivers flow and every sea, and all the springs and deep wells". Being the source of rivers and springs would seem logically to require that Oceanus was himself a freshwater river, and so different from the salt sea, and in fact Hesiod seems to distinguish between Oceanus and Pontus, the personification of the sea. However elsewhere the distinction between fresh and salt water seems not to apply. For example, in Hesiod Nereus and Thaumus, both sons of Pontus, marry daughters of Oceanus, and in Homer (who makes no mention of Pontus), Thetis, the daughter of Nereus, and Eurynome the daughter of Oceanus, live together. In any case, Oceanus can also to be identified with the sea.
Oceanus is represented, identified by inscription, as part of an illustration of the wedding of Peleus and Thetis on the early sixth century BC Atticblack-figure "Erskine" dinos by Sophilos (British Museum 1971.111-1.1). Oceanus appears near the end of a long procession of gods and goddesses arriving at the palace of Peleus for the wedding. Oceanus follows a chariot driven by Athena and containing Artemis. Oceanus has bull horns, holds a snake in his left hand and a fish in his right, and has the body of a fish from the waist down. He is closely followed by Tethys and Eileithyia, with Hephaestus following on his mule ending the procession.
Oceanus also appears, as part of a very similar procession of Peleus and Thetis' wedding guests, on another early sixth century BC Attic black-figure pot, the François Vase (Florence 4209). As in Sophilos' dinos, Oceanus appears at the end of the long procession, following after the last chariot, with Hephaestus on his mule bringing up the rear. Although little remains of Oceanus, he was apparently shown here with a bull's head. The similarity in the order of the wedding guests on these two vases, as well as on the fragments a second Sophilos vase (Athens Akr 587), suggests the possibility of a literary source.
Oceanus is depicted (labeled) as one of the gods fighting the Giants in the Gigantomachy frieze of the second century BC Pergamon Altar. Oceanus stands half nude, facing right, battling a giant falling to the right. Nearby Oceanus are fragments of a figure thought to be Tethys: a part of a chiton below Oceanus' left arm and a hand clutching a large tree branch visible behind Oceanus' head.
In Hellenistic and Roman mosaics, this Titan was often depicted as having the upper body of a muscular man with a long beard and horns (often represented as the claws of a crab) and the lower body of a serpent (cfr.Typhon). In Roman mosaics, such as that from Bardo, he might carry a steering-oar and cradle a ship.
Oceanus appears in Hellenic cosmography as well as myth. Cartographers continued to represent the encircling equatorial stream much as it had appeared on Achilles' shield.
Herodotus was skeptical about the physical existence of Oceanus and rejected the reasoning--proposed by some of his coevals--according to which the uncommon phenomenon of the summerly Nile flood was caused by the river's connection to the mighty Oceanus. Speaking about the Oceanus myth itself he declared:
As for the writer who attributes the phenomenon to the ocean, his account is involved in such obscurity that it is impossible to disprove it by argument. For my part I know of no river called Ocean, and I think that Homer, or one of the earlier poets, invented the name, and introduced it into his poetry.
Some scholars[who?] believe that Oceanus originally represented all bodies of salt water, including the Mediterranean Sea and the Atlantic Ocean, the two largest bodies known to the ancient Greeks. However, as geography became more accurate, Oceanus came to represent the stranger, more unknown waters of the Atlantic Ocean (also called the "Ocean Sea"), while the newcomer of a later generation, Poseidon, ruled over the Mediterranean Sea.
Late attestations for an equation with the Black Sea abound, the cause being - as it appears - Odysseus' travel to the Cimmerians whose fatherland, lying beyond the Oceanus, is described as a country divested from sunlight. In the fourth century BC, Hecataeus of Abdera writes that the Oceanus of the Hyperboreans is neither the Arctic nor Western Ocean, but the sea located to the north of the ancient Greek world, namely the Black Sea, called "the most admirable of all seas" by Herodotus, labelled the "immense sea" by Pomponius Mela and by Dionysius Periegetes, and which is named Mare majus on medieval geographic maps. Apollonius of Rhodes, similarly, calls the lower Danube the Kéras Okeanoío ("Gulf" or "Horn of Oceanus").
Hecataeus of Abdera also refers to a holy island, sacred to the Pelasgian (and later, Greek) Apollo, situated in the westernmost part of the Okeanós Potamós, and called in different times Leuke or Leukos, Alba, Fidonisi or Isle of Snakes. It was on Leuke, in one version of his legend, that the hero Achilles, in a hilly tumulus, was buried (which is erroneously connected to the modern town of Kiliya, at the Danube delta). Accion ("ocean"), in the fourth century AD Gaulish Latin of Avienius' Ora maritima, was applied to great lakes.
^One of the Oceanid daughters of Oceanus and Tethys, at Hesiod, Theogony351. However, according to Apollodorus, 1.2.3, a different Oceanid, Asia was the mother, by Iapetus, of Atlas, Menoetius, Prometheus, and Epimetheus.
^Although usually, as here, the daughter of Hyperion and Theia, in the Homeric Hymn to Hermes (4), 99–100, Selene is instead made the daughter of Pallas the son of Megamedes.
^Aeschylus (?), Prometheus Bound286–289, 395 (which describes the beast as "four-footed"). Hard, p. 40 suggests that Oceanus' steed is a griffin or griffin-like, while Gantz, p. 28, suggests griffin or hippocamp.
Anonymous, The Homeric Hymns and Homerica with an English Translation by Hugh G. Evelyn-White. Homeric Hymns. Cambridge, MA.,Harvard University Press; London, William Heinemann Ltd. 1914. Online version at the Perseus Digital Library.
Callimachus, Callimachus and Lycophron with an English translation by A. W. Mair ; Aratus, with an English translation by G. R. Mair, London: W. Heinemann, New York: G. P. Putnam 1921. Internet Archive.
Pausanias, Pausanias Description of Greece with an English Translation by W.H.S. Jones, Litt.D., and H.A. Ormerod, M.A., in 4 Volumes. Cambridge, Massachusetts, Harvard University Press; London, William Heinemann Ltd. 1918. Online version at the Perseus Digital Library.