Corinth sits on a very narrow isthmus between the Aegean proper and a long gulf that leads west and eventually into the Adriatic. Sailing around the Peloponnesus is about 400 miles - hence the attraction of crossing the isthmus.
In ancient times there was a 'haulway' here (a diolkos)- ships were taken across on rollers.
Even in ancient times, the idea of a canal was put forward, but no one could get it done.
In 1893, after 12 years of work by French and Greek companies, the canal opened.
It is about 6km in length with a water depth of 8m. It is about 25m wide.
After WWII the canal was clogged and unusable. Marshall plan aid to Greece put it back in working order.
The walls are fractured and rather unstable necessitating frequent repairs.
Apparently some of the remains of the haulway can be seen in certain spots.
Detail of the north end.
I think the yellow and black structure is one of the submersible bridges to allow road traffic to pass across the canal.
View looking south.
The road bridge you see is the main national highway.
For easier foot access to the canal and for the shops and bathrooms, you need to take an exit from the modern highway and cross the canal on the older highway.