Strabo Geography 9.4.2

[2] Next, then, after Halae, ¹ where that part of the Boeotian coast which faces Euboea terminates, lies the Opuntian Gulf. Opus is the metropolis, as is clearly indicated by the inscription on the first of the five pillars in the neighborhood of Thermopylae, near the Polyandrium: ² It is about fifteen stadia distant from the sea, and sixty from the seaport. Cynus is the seaport, a cape which forms the end of the Opuntian Gulf, the gulf being about forty stadia in extent. Between Opus and Cynus is a fertile plain; and Cynus lies opposite Aedepsus in Euboea, where are the hot waters of Heracles, and is separated from it by a strait one hundred and sixty stadia ³ wide. Deucalion is said to have lived in Cynus; and the grave of Pyrrha is to be seen there, though that of Deucalion is to be seen at Athens. Cynus is about fifty stadia distant from Mount Cnemis. The island Atalanta is also situated opposite Opus, and bears the same name as the island in front of Attica. It is said that a certain people in Eleia are also called Opuntians, but it is not worth while to mention them, except to say that they are reviving a kinship which exists between them and the Opuntians. Now Homer says that Patroclus was from Opus, ⁴ and that after committing an involuntary murder he fled to Peleus, but that his father Menoetius remained in his native land; for thither Achilles says that he promised Menoetius to bring back Patroclus when Patroclus should return from the expedition. However, Menoetius was not king of the Opuntians, but Aias the Locrian, whose native land, as they say, was Narycus. They call the man who was slain by Patroclus “Aeanes”; and both a sacred precinct, the Aeaneium, and a spring, Aeanis, named after him, are to be seen.