A canal through the Isthmus , the narrow land-bridge between the Peloponnese and the mainland of Greece, has been an issue since ancient times. The earliest plans date back to the 7th century BC. In the first century AD the Roman emperor Nero made a first attempt, by removing soil with a pickax. (see Corinth Canal)
It takes some adapting, the first time you look down the 90 meters.
It is deep, steep and narrow. All that into extremes. The actual depth of the water is 8 meters.
The canal is now mainly used for tourist boats. The maximum width for ships is 17,6 meters.