The family that used to own this land had a little shed erected in a caliche (limestone dirt) parking area. They provided a donations box, a trash can, a porta potty and a picnic table at the parking area. The trail down into the sunken grotto containing this natural wonder was steep, but fairly well maintained. Rumor was the family didn't really want the public using this swimming hole because teens kept diving off the 100 foot cliff into the pool below, scaring everyone to death. Every time that I went there in the late 70's with college friends I'd see boys jumping. I'd always watch anxiously for their heads to surface.
Finally, in the 80's Travis County acquired the land and made it a park. Now there are real restrooms up in the parking area and a $5 per vehicle entry fee. When you leave the unimpressive parking area and head down into the deep grotto formed by the collapse of a cave, you'll begin to hear the sound of water running over the edges of 100 foot high limestone cliffs. Because this was once an underground river, part of the Edwards Aquifer, the limestone cliffs that surround it, arch over it and form sort of a partial roof. The water falls from the spring fed creek overhead and hits the pool about 70 feet from its edges. Some swimmers like to lie on floats and let the water fall on their backs. I've tried that and found it painful.
In wet times the falls almost completely cover the semi-circular, over-arching cliffs. In dry times, like most of summer, the falls narrow to a 10 foot wide, 100 foot tall sprinkle. Half the circular pool is ringed with a beach-- that sandy beach being, in turn, flanked by tall trees that don't provide shade. The other 180 degrees of this circular, deep lagoon are sheltered by the remains of the cavern. This part, with its partial limestone roof stays wet with spring water seepage and supports colonies of maiden hair fern, columbines and carpet moss. The boulders are slippery and dangerous.
People are drawn to this over-arched section of the shore-line because it is shaded by the partial cavern roof. Each time I have gone I've seen visitors perched on the boulders behind the falls line enjoying the cool spray from their shaded balconies. The park discourages this activity as well as cliff diving. While the diving seems to have stopped, visitors can't seem to resist exploring the interesting area behind the water fall line, at the base of the over-arching cliffs.