On a healthy nine-hour layover in Panama City, I arranged a tour bus to see the Panama Canal ($30 which included: a long stop at a mall (blah), photo and souvenir shopping stops and finally to the Canal).
I was able to watch a cruise ship (Seven Seas Mariner) go through the full process. It was interesting to see how everything operates so smoothly. I’ve seen ships pass between the Puget Sound and the freshwater Lake Union at the Ballard Locks (Hiram M. Chittenden Locks) in Seattle, but on a much, much smaller scale. Those locks also have a very cool salmon ladder.
The Miraflores Locks also had a museum, which I only had about 15 minutes to rush through.
Here is a look at the ship passing through!
The other side
A Random Journey 