After riding the rivers and soaking up the sun at the water parks, consider a day trip to nearby San Antonio. The city is home to the Alamo , which in 1835 was the sight of one of the most important battles in the Texas Revolution. Here Texian and Tejano volunteers stood their ground in the converted missionary church, and while it was designed as a fort, it held out against the Mexican Army, led by Santa Anna. This is the most famous tourist spot in Texas!
The Alamo is open daily, except for Christmas Eve and Christmas Day, from 9am until 5:30pm Monday through Saturday, and 10am until 5:30pm on Sunday. During the summer months, the Alamo remains open until 7pm on Friday and Saturday. Admission is free.

Texas is a big place, but fortunately New Braunfels is centrally located so nothing is too far. Texas is a wide-open state too, so day trips can make for reasonably pleasant drives. Consider heading up to the state capital in Austin. It makes for a lovely trip up Interstate 35, where visitors can take in the state capitol building, see the University of Texas campus and even spend an evening listening to the unique sounds of Austin.