I came across two Yellow-bellied Water Snake cavorting in a small shaded puddle. The puddle was located in a dried out gully. Only the shade of nearby trees prevented this puddle from evaporating as well.
The two snakes were small, but one was slightly longer than the other. I would estimate that the bigger snake to be around 2ft/70cm in length, and the smaller snake to be closer 1.5ft/46cm.
The pool of water was divided somewhat, and each snake was swimming circles in its own side of the puddle. The pair swam round and round continuously as I watched.
Finally, I decided to move closer for some photographs. As I did, the larger of the two snakes immediately became aware of my presence and exited the puddle for some nearby vegetation. The smaller snake stayed and allowed me to photograph him.
When I came back by, around an hour later, one snake was still in the water. But, while I watched, he too crawled out puddle and into the safety of the bushes.