ἐναλίαν = ἐν + ἅλς (ἅλς = θάλασσα).
It's an ancient Greek phrase and refers to Cyprus (which is a land on the sea, i.e. island). The phrase is from the tragedy "Eleni" (produced in 412 B.C.) of Euripides and was also used by G. Seferis, the Greek nobelist, in his poem "Eleni".
In Euripides' tragedy the phrase was said by Teucer (a hero of The Troyan War) to Helen. They both are in Egypt outside the king's palace:
As to why I came to this royal palace, wanting to see the prophetess Theonoe, you be my patron, so I might obtain an oracle: how I should steer a favorable course to the island of Cyprus, where Apollo has declared I am to live, giving it the island name of Salamis in honor of that fatherland over there.