Ino, pursued by her husband, who had been driven mad by Hera because Ino had brought up the infant Dionysus, threw herself and Melicertes into the sea from a high rock between Megara and Corinth, and both were changed into marine deities: Ino as Leucothea, noted by Homer, and Melicertes as Palaemon.

The body of Melicertes was carried by a dolphin to the Isthmus of Corinth and deposited under a pine tree. Here it was found by his uncle Sisyphus, who had it removed to Corinth and, by command of the Nereids, instituted the Isthmian Games and sacrifices in his honor.

Palaemon appears for the first time in Euripides' Iphigeneia in Tauris, where he is already the "guardian of ships." The paramount identification among the Latin poets of the Augustan age is with Portunus, the Roman god of safe harbours, memorably in Virgil's Georgics. Ovid twice told the story of Ino's sea-plunge with Melicertes in her arms.

Ovid's treatment in his Fasti is the earliest to identify the Isthmus of Corinth as the location, though without literally naming it: "A land there is, shrunk within narrow bounds, which repels twin seas, and single in itself, is lashed by two-fold waters." In later Latin poets there are numerous identifications of Palaemon with the sanctuary at the Isthmus, where no archaeological evidence was found for a pre-Augustan cult.

Hyginus states both that Ino cast herself into the sea with her younger son by Athamas, Melicertes, and was made a goddess, and that Ino, daughter of Cadmus, killed her son Melicertes by Athamas, son of Aeolus, when she was fleeing from Athamas.

In Greco-Roman views, Palaemon is depicted as a dolphin-riding boy, or as a child with a triton tail.

No satisfactory origin of the name Palaemon has been given. The name means "the wrestler" and is an epithet of Heracles, with whom Melqart is identified by interpretatio graeca and referred to as the "Tyrian Herakles"; yet there does not appear to be any traditional connection between Heracles and Palaemon.

Melicertes being Phoenician, Palaemon has also been explained as the "burning lord" (Baal-haman), but there seems little in common between a god of the sea and a god of fire. The Romans identified Palaemon with Portunus, the harbour god, and some took the name Palaemon to mean "the honey eater."

In the late 2nd century CE, within the sanctuary of Poseidon at Isthmia, Pausanias saw a temple of Palaemon "...with images in it of Poseidon, Leucothea, and Palaemon himself. There is also what is called his Holy of Holies..." In company with Leucothea, Melicertes/Palaemon was widely invoked for protection from dangers at sea.

There remains considerable doubt whether the cult of Melicertes was of foreign — probably Phoenician — origin, introduced by Phoenician navigators on the coasts and islands of the Aegean and Mediterranean. For the Hellenes he is a native of Boeotia.

In 1956, excavations at Isthmia under the direction of Broneer uncovered the small sanctuary of Palaemon, which eventually included a tiny Roman round temple in the Corinthian order; it appeared on coins of Corinth in the 2nd century CE and was the successor to two earlier, more modest architectural phases. The foundations of the temple were found to lie over the starting-line of a late-5th- or early-4th-century BCE stadium. Worship was characterized by the dedication of hundreds of wheelmade oil lamps of a distinct type. A cult of Melicertes of great antiquity, possibly based on pre-Hellenic figures of Ino and Melicertes, was posited by Will just before the site's discovery, and refuted by Hawthorne in 1958.