In another German town south of Austin you will find more amazing history and amazing things to do. New Braunfels, about forty five minutes south, is often a place for the locals of Austin to run away to. Whether it's the first hot day of the Summer or just the only day off they were lucky enough to have, New Braunfels' Guadalupe and Comal Rivers are filled with tubers and fun. Tubing usually ranges in price from about $10-20 a tube depending on the style (single, double, cooler), and the rest is up to you. It's BYOB, snacks, and entertainment. Just remember your sunscreen and water as that afternoon Texas sun can really beat down on you.
New Braunfels also offers a great downtown with amazing restaurants such as the Gristmill, a hillside, barn-like restaurant, and amazing local country store style atmosphere. If you head down the road a bit there is even wine tasting at their local winery. The crafts and country store feel gives this small town an at home feel for the locals and it's visitors.
If you are looking for a real splash, a little further down Highway 35 you will find the largest waterpark in Texas, Schlitterbahn Waterpark Resort. Here they have rides for all ages including: wave pool, family tubing, and learn to surf on the Boogie Bahn Surfing ride. With three waterparks, Blastenhoff, Surfenberg, and Schlitterbahn West there is something for everyone. Definitely a great way to cool off during the summer heat. Here you can bring your own drink and food or you can partake in the foot long corn dogs, or corn on the cob just they way you like it.
New Braunfels is a great vacation destination and only being down the road from Austin you can make your trip a day or two or even a week.
For more on the visitors guide of New Braunfels visit http://www.newbraunfels.com/.