The Corinth Canal connects the Gulf of Corinth with the Saronic Gulf in the Aegean Sea. It cuts through the narrow Isthmus of Corinth and separates the Peloponnesian peninsula from the Greek mainland. The builders dug the canal through the Isthmus at sea level; no locks are employed. It is 6.4 kilometres (4.0 mi) in length and only 21.4 metres (70 ft) wide at its base.

The rock walls, which rise 90 metres (300 ft) above sea level, are at a near-vertical 80° angle. The canal is crossed by a railway line, a road and a motorway at a height of about 45 metres (148 ft).

Although the canal saves the 700-kilometre (430 mi) journey around the Peloponnese, it is too narrow for modern ocean freighters, as it can only accommodate ships of a width of up to 16.5 metres (54 ft) and a depth of 7.3 metres (24 ft). Ships can only pass through the canal one at a time on a one-way system. Larger ships have to be towed by tugs. The canal is nowadays mostly used by tourist ships; 11,000 ships per year travel through the waterway. [Source]