tidal waterway (canals and inland waterways) across the Isthmus of Corinth (Corinth, Isthmus of) in Greece, joining the Gulf of Corinth in the northwest with the Saronic Gulf in the southeast. The isthmus was first crossed by boats in 600 BC when Periander built a ship railway, small boats being carried on wheeled cradles running in grooves. This system may have been used until the 9th century. Work on the canal began in 1882, and it opened in 1893. The canal is 6.3 km (3.9 miles) long and has a water depth of 8 metres (26 feet); its width varies from a minimum of 21 metres (69 feet) at the bottom to a maximum of 25 metres (82 feet) at the water's surface. The canal has brought great economic benefits to the ports of Posithonía at its northwest end and Isthmía at its southeast end.