Psamathe (Greek: Ψάμαθη, from ψάμαθος "sand of the sea-shore") was a Nereid in Greek mythology, i.e., one of the fifty daughters of Nereus and Doris. The goddess of sand beaches, Psamathe was the wife of Proteus and the mother of Phocus by Aeacus.
Some translations of Ovid have the name as Psamanthe.
Psamathe (Nereid) Wikipedia
Psamathe has a moon named after her.