Comment by HarHarVeryFunny

Why would gravity require a water supply other than what's already in the canal?

o To go up you sail in, close the gate behind you, and let water into the lock from the higher level until you can open that gate and sail out

o To go down you sail in, close the gate behind you, and let water out until it has dropped to the lower level and you can open that gate and sail out

At, least, this is how normal canals/locks work.

What's special about the Panana canal ?