Strabo Geography 2.5.22

[22] Here too is the strait, seven stadia in length, which is between Sestos ¹ and Abydos, ² and through which the Aegaean and Hellespont communicate with another sea to the north, named the Propontis, ³ and this again with another called the Euxine. This latter is, so to speak, a double sea, for towards its middle are two projecting promontories, one to the north, on the side of Europe, and the other opposite from the coast of Asia, which leave only a narrow passage between them, and thus form two great seas. The European promontory is named Criu-metopon; ⁴ that of Asia, Carambis. ⁵ They are distant from each other about 2500 stadia. ⁶ The length of the western portion of this sea ⁷ from Byzantium to the outlets of the Dnieper is 3800 stadia, its breadth 2000. Here is situated the Island of Leuca. ⁸ The eastern portion is oblong and terminates in the narrow recess in which Dioscurias is situated. In length it is 5000 stadia, or rather more, and in breadth about 3000. The entire circumference of the Euxine is about 25,000 stadia. Some have compared the shape of its circumference to a Scythian bow when bent, the string representing the southern portions of the Euxine, (viz. the coast, from its mouth to the recess in which Dioscurias is situated; for, with the exception of Carambis, the sinuosities of the shore are but trifling, so that it may be justly compared to a straight line,) and the remainder [of the circumference representing] the wood of the bow with its double curve, the uppermost very much rounded, the lower more in a straight line. So this sea forms two gulfs, the western much more rounded than the other.