Only twenty minutes from downtown Austin lies McKinney Falls State Park. Even though the park is fairly small, there are ample opportunities for hiking, swimming, fishing, and camping. Its also a great place to take your dog, even though he is supposed to be on the leash at all times. Due to how close the falls are to the parking areas, McKinney Falls makes a great weekend day trip.
Both the Upper and Lower Falls provide great swimming, each with rocky beaches facing the respective falls. The trail runs along the top of the falls following the ridge line. Further along the trail, there are some additional paths that take you away from the water and into the hills that makes for some great hiking where you feel like you have the area to yourself as most people stay near the water.