And just so everyone remembers this, Lake Gatún is the primary water source for fresh water in the area.

That little facet plays a non-zero role in any discussion about travel along the canal.

And for those wondering how a canal “uses” water. At some point a lake that was never connected to the ocean, has some small amount of it discharge into the ocean every time a boat moves through the canal.

You can use all kinds of partitions and fancy pumps to reduce the amount of salt water that gets in and fresh water that leaves, but you can never get it to zero. There will always be some salt water getting into the lake and some fresh water making it to the ocean. And that value begins to add up when you have thousands of boats.