Things to Do Think of the park as Austin’s backyard; we’re just 13 miles from the state capitol. Here you can camp, hike, mountain or road bike, geocache, go bouldering, and picnic. You can also fish and swim in Onion Creek. Onion Creek can flood after rainfall. Beware of the creek’s flow; contact the park for current creek conditions. Read through our swimming safety tips before you visit. Stay overnight Stay at one of 81 campsites (all with water and electric hookups). Or rent one of our six newly remodeled cabins. We also have a primitive youth camping area, for use by nonprofit sponsored youth groups. Hiking and biking Hike or bike nearly nine miles of trails. The 2.8-mile Onion Creek Hike and Bike Trail has a hard surface, good for strollers and road bikes. We have an all-terrain wheelchair for use in the park; email us to reserve the chair for your visit. Take the Rock Shelter Trail (only for hikers) to see where early visitors camped. Fishing and swimming Go fishing in Onion or Williamson creeks. You do not need a license to fish from shore in a Texas state park. Download