Canal transit

It took most of a day to transit through the Panama Canal. It is not a level journey, so in several places there were "locks" to move the ship up or down to the next water level.



I will confess that I never did understand the concept of a lock prior to seeing one. So for those of you who, like me, don't know what it is:
The ship drives into a big bathtub, which they then fill or drain depending on whether you need to go up or down. The boat floats up or down with the water, they open the forward end of the bathtub again, and you drive out to the next lock.