1. A son of Poseidon and Amymone, of Argos, a famous navigator, and father of Proetus and Damastor (Apollon. Rhod. i. 136, &c.; Schol. ad Apollon. Rhod. iv. 1091). He is the reputed founder of the town of Nauplia, which derived its name from him (Paus. ii. 38. § 2, iv. 35. § 2; Schol. ad Eurip. Orest. 54). He is also said to have discovered the constellation of the great bear. (Theon, ad Arat. Phaen. 27; Paus. viii. 48. § 5; Strab. viii. p. 368.)

2. A son of Clytoneus, was one of the Argonauts and a descendant of Nauplius, No. 1. (Apollon. Rhod. i. 134.)

3. A king of Euboea, and father of Palamedes, Oeax and Nausimedon, either by Clymene or Philyra or Hesione (Apollod. ii. 1. § 4). Clymene was a daughter of Catreus, and she and her sister Aerope had been given by their father to Nauplius, who was to carry them to some foreign country; but Nauplius married Clymene, and gave Aerope to Pleisthenes, who became by her the father of Agamemnon and Menelaus (Apollod. iii. 2. § 2). His son Palamedes had been condemned to death by the Greeks during the siege of Troy, and as Nauplius considered his condemnation to be an act of injustice, he watched for the return of the Greeks, and as they approached the coast of Euboea, he lighted torches on the most dangerous part of the coast. The sailors thus misguided suffered shipwreck, and perished in the waves or by the sword of Nauplius (Philostr. Her. x. 11; Schol. ad Eurip. Orest. 422; Tzetz, ad Lycoph. 384; Hygin. Fab. 116). He is further said to have wreaked his vengeance on the Greeks by sending false messages to the wives of the heroes fighting at Troy, and thus to have led them to faithlessness towards their husbands or to self destruction. (Eustath. ad Hom. p. 24; Tzetz, l.c.; Paus. i. 22. § 6.)