Okeanos (Oceanus), the Ultimate Solution, makes a few appearances in some comments by Homer the principal pedagogical text of ancient Greece. Two especially from the Iliad Book XIV stand out and receive ancient commentary [the emphases are mine]:
XIV, 200 (repeated at XIV, 301) where Hera says,
For I am going to see the limits of fertile earth, Okeanos begetter of gods and mother Tethys …
XIV, 244 where Hypnos says,
Another of the everlasting gods would I easily send to sleep, even the streams of river Okeanos who is the begetter of all; but Zeus son of Kronos would I not approach, nor send to sleep, except that he himself so bid me.
In the context of reporting on the suppositions of Thales, Aristotle (in the Metaphysics Book I, 3) does not fail to mention the picture given by Homer of Okeanos as the primordial origin of all things:
There are some who think that the very ancient and indeed first speculators about the gods, long before the present age, made the same supposition about nature [as Thales]; for they wrote that Okeanos and Tethys were the parents of coming-to-be, and the oath of the gods water — that which by the poets themselves is called Styx; for what is oldest is most honourable, and the most honourable thing is used as an oath.
These passages in Homer are rather unusual when compared with other Greek cosmogonic myths as one finds, for example, in Hesiod or the Orphic poets. Untypically, they seem to present a picture of the great encircling primordial Sea that is found more typically in Egyptian or Babylonian cosmogonies. Thus the supposition by some that the Homeric passages provide indirect evidence for an early influence and connection with ancient Near Eastern beliefs:
It was part of those beliefs, too, that the world originated from primeval water; the isolated Homeric passages could, then, be a reference to that basic near-eastern assumption. The concept of the encircling river had, of course, become assimilated in Greece at a far earlier date.*
Note: The translations here all taken from Kirk, Raven and Schofield, The Presocratic Philosophers, Second ed.
* Kirk, Raven & Schofield, p. 16-17.