BABY NEPHEW NOAH AND OTHER MEMBERS OF MY FAMILY COOLING OFF AT RIO VISTA FALLS. Looking for a cool way to spend time on a hot central Texas day? Rafting the beautiful San Marcos River is about as cool as it gets. The spring-fed river water stays a constant 72 degrees all year round, which can feel like ice on a blistering hot afternoon in Texas. Spend a relaxing summer afternoon soaking up the rays while cooling off in a spring-fed river float. AND BEST OFF ALL IT’S FREE . JUST PLEASE BE CAREFULL WITH YOUR LITTLE ONES .THIS IS ONE OF MY FAVORITE PLACES TO GO COOL OFF .