Fresh from constructing a sea-level canal through the flat Egyptian sand, de Lesseps was determined, without having set foot in Panama and after only the vaguest of topographical studies, that his project through the mountainous central American isthmus would also be a sea-level canal, requiring no locks to cope with changes in altitude.

ECONOMIST: The Panama Canal

The key was not to try to dig a Suez-type of canal, a great sea-level trench from ocean to ocean, but to create a lock-and-lake canal, where the ships are lifted up by a series of locks to a man-made lake, and then they sail across that lake, and then they are set back down on the other side by another series of locks.

FORBES: Fact and Comment

It is also short of water, which must be constantly replenished, because much of the canal is above sea-level.

ECONOMIST: The Panama canal