Homer uses the word wine-dark (οἶνοψ) for the sea, for example in the Odyssey
νῦν δ᾽ ὧδε ξὺν νηὶ κατήλυθον ἠδ᾽ ἑτάροισιν
πλέων ἐπὶ οἴνοπα πόντον ἐπ᾽ ἀλλοθρόους ἀνθρώπους,
Now I have come with my ship and companions, sailing over the wine dark sea to men who speak another language.
I have always taken this to refer to the translucence of the sea. Unlike the murky waters round England, the sea round Greece has a beautiful translucence like red wine. This is my preferred reading but an alternative suggested itself to me. Homer calls wine flame-like (αἰθοψ) usually translated as sparkling. So if wine is sparkling and the sea looks like wine, then may be οἶνοψ could mean sparkling. (That’s not sparkling like champagne but sparkling as the light gleams off its surface).
‘Ἰδομενεῦ περὶ μέν σε τίω Δαναῶν ταχυπώλων
ἠμὲν ἐνὶ πτολέμῳ ἠδ᾽ ἀλλοίῳ ἐπὶ ἔργῳ
ἠδ᾽ ἐν δαίθ᾽, ὅτε πέρ τε γερούσιον αἴθοπα οἶνον
Ἀργείων οἳ ἄριστοι ἐνὶ κρητῆρι κέρωνται.
Idiomeneus, I honour you especially of the long robed Danaans both in war and in any other matter and in a feast when the best of the Argives mix the flame-like wine of the elders in the mixing bowl.