She said no, and the sea had to send a diplomat.
Amphitrite, one of the fifty Nereids — daughters of the old sea-god Nereus and the Oceanid Doris — was dancing with her sisters on Naxos when Poseidon saw her. She refused him and fled to the far west, to the Atlas mountains at the edge of the world. He sent messengers after her, and the one who found her and talked her round was a dolphin, named Delphinus, who escorted her back and negotiated the marriage. Poseidon set the dolphin among the stars in gratitude.
That constellation, Delphinus, is a small compact group between Aquila and Pegasus, and it is one of very few constellations with a courtship story attached rather than a hunt or a battle. Its two brightest stars carry the names Sualocin and Rotanev, inserted into the star catalogues in 1814 by the assistant astronomer Niccolò Cacciatore at Palermo — his own name, Latinised as Nicolaus Venator, spelled backwards. It went unnoticed for decades and the names are now official.
Queen, not consort
In the Odyssey she is not primarily Poseidon's wife but the sea itself as an active power: Homer speaks of "loud-roaring Amphitrite", of the fish she feeds and rears in thousands, and of her waves breaking. That usage — her name as a metonym for the sea — is older than her role as a spouse, and in Hesiod she is listed among the Nereids before any marriage is mentioned.
Her authority in the underwater court is real. When Theseus dives into the sea to prove his descent from Poseidon, in Bacchylides' seventeenth dithyramb, it is Amphitrite who receives him: she wraps him in a purple cloak and sets on his head the dark garland she had received at her own wedding from Aphrodite, and he surfaces dry. The proof of divine parentage is issued by the queen, not the king.
She is also, in the Odyssey, credited with keeping the sea's monsters, and Odysseus fears that she may send one against him — which makes her something more formidable than the decorative figure she becomes in later art.
Her son and her family
Her child by Poseidon is Triton, the merman herald with the conch, and later sources add daughters: Rhode, associated with Rhodes, and Benthesikyme.
The other well-known story involving her is a jealousy: Scylla was, in one version, a beautiful nymph whom Poseidon desired, and Amphitrite poisoned the pool where she bathed, turning her into the barking six-headed monster of the strait. Ovid gives the same transformation to Circe jealous over Glaucus, which is the better-known account. The doubling shows how a single monster's origin story could be attached to whichever divine rivalry a poet preferred.
In art and cult
She appears in Greek and Roman art riding beside Poseidon in a chariot drawn by hippocamps — horses with fish tails — attended by Tritons and Nereids. The type is called a marine thiasos, a sea-procession, and it became one of the most popular subjects for Roman mosaics and sarcophagi, including a famous mosaic from Constantine in Algeria and the great pavements at Piazza Armerina in Sicily. Poussin and Raphael and the Trevi Fountain's designers all worked in that tradition; the Trevi's central figure is Oceanus rather than Poseidon, but the composition descends from the same source.
Cult of her own is thin. She was worshipped alongside Poseidon at some coastal sites and appears in the offerings at Delos and at Tenos, and there is an old and important cult of the pair on the island of Tenos in particular. She is a genuine goddess with dedications, not merely a literary figure, but she has no great sanctuary in her own name.
Her attributes are a crab-claw crown — real crab pincers set in her hair, one of the more distinctive headpieces in Greek art — a net, and sometimes a trident or a dolphin.
Salacia is not her translation
The Roman Salacia, consort of Neptune, is a separate Italic figure whose name is connected with sal, salt, or with salax, and who was associated with springwater and salt water. Varro pairs her with Neptune; she has almost no mythology. When Latin poets tell Greek stories they generally simply use Amphitrite's name, which is the clearest sign that the identification with Salacia was formal rather than substantive.
Where she is now
Her name has gone almost entirely to the sea in a technical register: amphitrite is a genus of marine bristle worms; the name has been used for ships, including several French naval vessels, and for a crater on Mars. She is otherwise a rare figure in modern fiction, generally appearing as Poseidon's wife in a supporting role — the Percy Jackson books give her a brief, coldly polite scene that plays on her being the wife of a serially unfaithful god, which is fair to the tradition.
What has not survived at all is the Homeric usage in which her name simply means the sea and its roar. That is the oldest thing about her and it is now invisible outside the Greek text.
Crab claws, Nereid ranks, and life outside her husband’s frame
What is a Nereid, exactly?
One of the fifty daughters of Nereus, the "old man of the sea", a shape-shifting prophetic deity of the pre-Olympian generation, and Doris. They are benevolent sea-nymphs who help sailors, and Hesiod lists all fifty names in the Theogony, which is one of the poem's more remarkable feats of versified cataloguing. The most famous besides Amphitrite is Thetis, mother of Achilles, and their group appearance to mourn with Achilles in Iliad 18 is one of the poem's most memorable images.
Why does she have crab claws in her hair?
It is a distinctive identifying attribute rather than a symbol with a stated meaning — no ancient source explains it. Practically, it distinguishes her instantly from other draped female figures in a crowded marine scene, which is exactly what an attribute is for. Similar logic gives Triton his conch and the Nereids their sea-creature mounts.
Is she ever shown without Poseidon?
Occasionally on vases with the Nereids, and in the Theseus dive scene, which is her strongest independent appearance. But the overwhelming majority of her depictions are as half of a pair, and Roman art in particular treats her as the female component of a marine couple. That imbalance is a fair reflection of the textual record.
Does she appear in the Odyssey's monsters chapter?
She is invoked around it. Odysseus, having heard of Scylla and Charybdis, fears that Amphitrite may be nourishing some further monster against him, and Homer earlier calls the whales and sea-beasts hers. She is not a character in those episodes but the poem treats her as the authority behind what lives in the water, which is more agency than her later reputation as a consort suggests.