according to Hesiod (Theogony 243) and Apollodorus i a Nereid, though in other places Apollodorus calls her an Oceanid.
She is represented as the wife of Poseidon and the goddess of the sea (the Mediterranean), and she is therefore a kind of female Poseidon. In the Homeric poems she does not occur as a goddess, and Amphitrite is merely the name of the sea.
The most ancient passages in which she occurs as a real goddess is that of Hesiod above referred to and the Homeric hymn on the Delian Apollo, where she is represented as having been present at the birth of Apollo.
When Poseidon sued for her hand, she fled to Atlas, but her lover sent spies after her, and among them one Delphinus, who brought about the marriage between her and Poseidon, and the grateful god rewarded his service by placing him among the stars.
When afterwards Poseidon showed some attachment to Scylla, Amphitrite jealousy was excited to such a degree, that she threw some magic herbs into the well in which Scylla used to bathe, and thereby changed her rival into a monster with six heads and twelve feet.
She became by Poseidon the mother of Triton, Rhode, or Rhodes, and Benthesicyme. (Theogony of Hesiod 930, etc. Apollodorus i) Later poets regard Amphitrite as the goddess of the sea in general, or the ocean. ( Metamorphoses by Ovid I)
Amphitrite was frequently represented in ancient works of art; her figure resembled that of Aphrodite, but she was usually distinguished from her by a sort of net which kept her hair together, and by the claws of a crab on her forehead. She was sometimes represented as riding on marine animals, and sometimes as drawn by them.
The temple of Poseidon on the Corinthian isthmus contained a statue of Amphitrite and her figure appeared among the relief ornaments of the temple of Apollo at Amyclae, on the throne of the Olympian Zeus, and in other places.
We still possess a considerable number of representations of Amphitrite. A colossal statue of her exists in the Villa Albani, and she frequently appears on coins of Syracuse, The most beautiful specimen extant is that on the arch of Augustus at Rimini.
From The Homeric Hymns: Hymn To Apollo
"When she (Leto) had sworn and done that oath, then Delos was glad in the birth of the Archer Prince. But Leto, for nine days and nine nights continually was pierced with pangs of child-birth beyond all hope. With her were all the Goddesses, the goodliest, Dione and Rheia, and Ichnæan Themis, and Amphitrite of the moaning sea, and the other deathless ones—save white-armed Hera. Alone she wotted not of it, Eilithyia, the helper in difficult travail. For she sat on the crest of Olympus beneath the golden clouds, by the wile of white-armed Hera, who held her afar in jealous grudge, because even then fair-tressed Leto was about bearing her strong and noble son."
From The Theogony of Hesiod
(ll. 240-264) And of Nereus and rich-haired Doris, daughter of Oceanus the perfect river, were born children, passing lovely amongst goddesses, Ploto, Eucrante, Sao, and Amphitrite, and Eudora, and Thetis, Galene and Glauce, Cymothoe, Speo, Thoe and lovely Halie, and Pasithea, and Erato, and rosy-armed Eunice, and gracious Melite, and Eulimene, and Agaue, Doto, Proto, Pherusa, and Dynamene, and Nisaea, and Actaea, and Protomedea, Doris, Panopea, and comely Galatea, and lovely Hippothoe, and rosy-armed Hipponoe, and Cymodoce who with Cymatolege and Amphitrite easily calms the waves upon the misty sea and the blasts of raging winds, and Cymo, and Eione, and rich-crowned Alimede, and Glauconome, fond of laughter, and Pontoporea, Leagore, Euagore, and Laomedea, and Polynoe, and Autonoe, and Lysianassa, and Euarne, lovely of shape and without blemish of form, and Psamathe of charming figure and divine Menippe, Neso, Eupompe, Themisto, Pronoe, and Nemertes who has the nature of her deathless father. These fifty daughters sprang from blameless Nereus, skilled in excellent crafts.