Extreme tides and rocks don't make for fun beaches in the city. Power is delivered through the slit marked by the arrows. Once in the lock, you don't know what size ship will follow you. Entrance to a lock. A vehicle bridge can swing in front of the lock doors if needed.
Dual doors allow using only the amount of water needed for a given size ship.
The walls of the locks are well worn, and softer than one would expect. Widening a critical portion of the canal to allow two-way traffic. Inside the Canal Commission administration building.