Amphitrite (Aμφιτρίτη) was a sea-goddess, wife/consort to Poseidon-Neptune and thus the Queen of the Sea. Eustathius said that Poseidon first saw the "loud moaning Amphitrite" dancing among the Nereids at Naxos and carried her away. In other versions of the myth, however, she fled from his advances to Atlas "at the farthest ends of the sea." It was there that Poseidon's dolphin, having sought Amphitrite through all the islands of the sea, found her and spoke persuasively and convincingly for Poseidon. According to Hyginius the dolphin was rewarded for this service by being placed among the stars as the constellation Delphinus.

It is actually Hesiod's Theogony that tells us Amphitrite was a Nereid; according to Apollodorus she was the daughter of Oceanid and Tethys and thus an Oceanid. Amphitrite’s children by Neptune were Triton, a merman; Rhode, goddess of the island of Rhodes; and, according to Apollodorus, Benthesikyme, wife of Enalos; and seals and dolphins as well. The fifth-century BC Greek lyric poet Bacchylides says that Theseus (founder-king of Athens fathered by both Poseidon and Aegeus with whom his mother Aethra had slept the same night) saw "august ox-eyed Amphitrite" dancing with the daughters of Nereus in his father's halls beneath the sea, who later put her wedding wreath around him.

Although Amphitrite was demoted from Neptune's wife to merely his consort by the Olympic gods and goddesses, early on she was of far greater mythological importance. In the anonymous ancient Greek ("Homeric") hymn to Delian Apollo, she appears at Apollo's birth among "all the chiefest of the goddesses, Dione and Rhea and Ichnaea and Themis and loud-moaning Amphitrite." Eventually she became the personification of the sea itself and was rarely linked with her husband except when he was explicitly considered as the god who ruled the sea.