East Bay of Sidrah

The eastern shore of the Gulf of Sidra opens along Libya's central Mediterranean coast, forming one lobe of the broad indentation ancients called Greater Syrtis. It runs about 439 kilometres from Boreum on the east to Cephalae on the west, reaches some 177 kilometres inland, and encloses roughly 57,000 square kilometres. The city of Sirte lies on the western shore. Unlike the more fertile country of Tripolitania farther west, the landward margin of the gulf was a featureless plain.

For sailors, the gulf joined useful traffic with a reputation for hazard. Its sandbanks, frequent spells of calm, powerful north winds and few ports between Cyrene and Carthage made navigation cautious rather than impossible. Tides set up a strong current of about three knots. Roman writers warned that shallow shelves could trap ships, and Strabo described Cato the Younger's march of 47 BC across deep, scorching sand. Tuna fishing centred on the gulf for centuries, supporting communities where fishing joined coastal exchange.