Back in elementary school, I was told the great dividing line between tortoises and turtles was that turtles are aquatic and tortoises are terrestrial. Obviously there are exceptions to this rule to greater or lesser degrees, but the first time I saw a Galapagos tortoise (Geochelone elephantopus) wallowing in a pool at the Philadelphia Zoo I was a bit surprised. This is a normal behavior for these giant tortoises, though, and they seem to enjoy spending time in the bath.