Twin Falls & Sculpture Falls
Just west of Mopac, Twin Falls is the perfect weekend respite from the heat -- when water levels are high. This hangout (which gets pretty crowded on weekends) is located along the Barton Springs Greenbelt, and just a short hike from Sculpture Falls. Park on the access road of 360 South, wear good shoes since the terrain is uneven, and for the love of Smokey, don’t litter. A 20-minute hike west from Twin Falls is the equally cool Sculpture Falls. The water varies in depth, but most people can be seen sitting in shallow areas but there is a small bluff for cliff jumping. Alcohol is allowed here and at Twin Falls, so pack a little ice chest.
Mansfield Dam Park
Just miles from Downtown Austin, Mansfield Dam Park has everything one could hope for: clean water, clean bathrooms... oh, and lots of open space. There are boats around but the area for swimming and floating is sectioned off, and perfect for taking in views of Lake Travis.