The partially marked Cliff Trail goes past the unassuming ‘Origin of Sex’ painting, around the northern end of Female Hill and into a deep and mysterious hidden valley. This trail also passes an amazing natural cistern (in a rock grotto near the northwestern corner of Female Hill) that has held water year-round for as long as anyone can remember.

The San believe this natural tank is inhabited by a great serpent with twisted horns, so visitors should warn the occupant of their approach by tossing a small stone into the water. This impressive feature is also flanked by rock art.