Strabo Geography 8.2.3

[3] The Corinthian Gulf begins, on the one side, at the outlets of the Evenus (though some say at the outlets of the Acheloüs, the river that separates the Acarnanians and the Aetolians), and, on the other, at Araxus; ¹ for here the shores on either side first draw notably nearer to one another; then in their advance they all but ² meet at Rhium and Antirrhium, where they leave between them a strait only about five stadia in width. Rhium, belonging to the Achaeans, is a low-lying cape; it bends inwards (and it is in fact called “Sickle “). ³ It lies between Patrae and Aegium, and possesses a temple of Poseidon. Antirrhium is situated on the common boundary of Aetolia and Locris; and people call it Molycrian Rhium. ⁴ Then, from here, the shoreline on either side again draws moderately apart, and then, advancing into the Crisaean Gulf, it comes to an end there, being shut in by the westerly limits of Boeotia and Megaris. ⁵ The perimeter of the Corinthian Gulf if one measures from the Evenus to Araxus, is two thousand two hundred and thirty stadia; but if one measures from the Acheloüs, it is about a hundred stadia more. Now from the Acheloüs to the Evenus the coast is occupied by Acarnanians; ⁶ and thence to Antirrhium, by Aetolians; but the remaining coast, as far as the Isthmus, belongs to ⁷ the Phocians, the Boeotians and Megaris—a distance of one thousand one hundred and eighteen stadia. The sea from Antirrhium as far as the Isthmus ⁸ is called Alcyonian, it being a part of the Crisaean Gulf. Again, from the Isthmus to Araxus the distance is one thousand and thirty stadia. Such, then, in general terms, is the position and extent of the Peloponnesus, and of the land that lies opposite to it across the arm of the sea as far as the recess; and such, too, is the character of the gulf that lies between the two bodies of land. Now I shall describe each part in detail, beginning with the Eleian country.

[3] The Corinthian Gulf begins from the mouths of the Evenus, ¹ (some say from the mouths of the Achelous, ² which is the boundary between the Acarnanes and Aetoli,) and from the promontory Araxus. For there the shores on both sides first begin to contract, and have a considerable inclination towards each other; as they advance farther onwards they nearly meet at Rhium ³ and Antirrhium, ⁴ leaving a channel of only about 5 stadia between them.

Rhium is a promontory of Achaia, it is low, and bends inwards like a sickle, (indeed it has the name of Drepanum, or the Sickle,) and lies between Patrae ⁵ and Aegium, ⁶ on it there is a temple of Neptune. Antirrhium is situated on the confines of Aetolia and Locris. It is called Rhium Molycrium. From this point the sea-shore again parts in a moderate degree on each side, and advancing into the Crissaean Gulf, terminates there, being shut in by the western boundaries of Boeotia and Megaris.

The Corinthian Gulf is 2230 stadia in circuit from the river Evenus to the promontory Araxus; and if we reckon from the Achelous, it would be increased by about 100 stadia.

The tract from the Achelous to the Evenus is occupied by Acarnanians; next are the Aetoli, reaching to the Cape Antirrhium. The remainder of the country, as far as the isthmus, is occupied by Phocis, Boeotia, and by Megaris, it extends 1118 stadia.

The sea from Cape Antirrhium as far as the isthmus is [the Crissaean Gulf, but from the city Creusa it is called the Sea of] Alcyonis, and is a portion of the Crissaean Gulf. ⁷ From the isthmus to the promontory Araxus is a distance of 1030 stadia.

Such in general then is the nature and extent of the Peloponnesus, and of the country on the other side of the strait up to the farther recess of the gulf. Such also is the nature of the gulf between both.

We shall next describe each country in particular, beginning with Elis.