Hamilton Pool Preserve is a natural pool that was created when the dome of an underground river collapsed due to massive erosion thousands of years ago. The pool is surrounded by huge slabs of limestone that rest by the water's edge; large stalactites grow from the ceiling high above. Hamilton Creek spills out over limestone outcroppings to create a 50 foot waterfall as it plunges into the head of a steep box canyon. The waterfall never completely dries up, but in dry times it does slow to a trickle. However, the pool's water level stays pretty constant, even during periods of drought.
The pool is located about 37 km west of Austin, Texas off Highway 71. Since the 1960s, Hamilton Pool has been a favorite summer swimming spot for Austin visitors and residents.
The preserve is home to the Golden-Cheeked Warbler, and a great variety of other birds. The diverse vegetation of Hamilton Pool ranges from semi-arid species in the uplands to riparian species in the canyon. The uplands of the preserve are a juniper and oak savannah with a variety of native grasses and wildflowers. Several rare plant species including canyon mock-orange, red bay (western-most colony of this eastern species), and chatter box orchid are known to occur in the canyon areas along Hamilton Creek.