Hilly banks flank Barton Springs, a 1,000-foot-long, spring-fed swimming hole just south of the river in Austin
. Crystalline waters keep a steady chill at 68 degrees all year round, which makes the pool Austin’s unofficial living room during summer’s scorching heat. A historic site, wedged into Zilker Park, the springs attracts a cross section of swimmers year round: Expect to see both triathletes training and kids splashing. Keep an eye out for its most famous resident—an endangered albino salamander.