With the rear gates closed, water is channeled into the lock and boils up from several holes in the floor of the chamber.

Interestingly, no pumps are used to move water through the locks. Gravity alone drains water from higher in the canal to our lock, raising us up. Eventually, something like 50,000 gallons of fresh water will be lost to the sea for each ship that makes the trip.

At the top right of the picture, the cables from the the port side mules are barely visible.