This natural pool was created when the dome of an underground river collapsed due to massive erosion thousands of years ago.
Since the 1960s, the pool has been a popular summer swimming spot for foreign visitors and local residents. It consists of 232 acres (0.94 km2) of protected natural habitat featuring a jade green pool into which a 50-foot (15 m) waterfall flows. The natural pool and creek are not chemically treated, so water quality is monitored regularly and swimming is occasionally restricted.
Ecology
The pool is surrounded by large slabs of limestone that rest by the water's edge; large stalactites grow from the ceiling high above. The ceiling and surrounding cliffs of the grotto are home to moss, maidenhair fern and cliff swallows. The Ashe juniper (cedar) uplands of the preserve are home to the endangered golden-cheeked warbler. The preserve is also the home to chatterbox orchid (Epipactis gigantea) and the eastern red bay (Persea borbonia).
Filming location
The 1990 movie The Hot Spot, with Jennifer Connelly and Don Johnson; the 2007 film Teeth; the 2010 film Predators; the 2011 film The Tree of Life; and the 2015 music video for the song Charlie Gray by the Dallas-based indie-rock band Valise all filmed scenes at the natural pool.
Image source: http://www.buzzfeed.com/ariellecalderon/surreal-places-in-america-you-need-to-visit-before-you-die?utm_term=.ivwBLzJjOY&sub=2903267_2579387