Barton Springs is Austin's best known pool. Donated to the city in 1917, it sits in the middle of Zilker Park and is fed by a natural spring. 

For swimmers, this means the pool water stays at a chilly 68 degrees year round. On the plus side, the water is not treated with any chemicals. On the down side, a combination of algae and silt routinely floats to the water's surface on sunny days and can be a nuisance for swimmers, getting in their eyes and swimsuits.

The irregularly shaped pool is about 1,000 feet in length and 150 feet at its widest point. There's an eighth-mile marker for lap swimmers. There's no pace clock to time laps, but there is a regular clock placed in the middle of the pool. There are also no lap lanes at the pool, which can cause lap swimmers to bump into each other. 

Also, during peak hours, generally from noon to 7 p.m. from the late spring to early fall, recreational swimmers and waders invade the pool and its expansive grassy shores, wreaking havoc on lap swimmers trying to navigate in anything resembling straight lines. This discourages some lap swimmers, like Austin resident Cary Cluett, from exercising at Barton Springs.

"I enjoy just going to swim at Barton Springs more than swimming laps. I like looking down and seeing a blue line in the middle of the pool," Cluett said. "I enjoy the fact that I don't have to look up and worry about whether or not somebody's going to hit me head on."

But Leslie Botts, an outdoor swimmer in Ausin since the late 1970s, said she prefers to do laps at Barton Springs and finds conventional pools confining.

"When I go to Barton's, it's not just to exercise and as a stress release but also for spiritual reasons," Botts said. "There's just something about being in Barton's that no matter what's going on before I swim that when I finish I feel great. And it's more than just the benefits of physical exercise."

Calling herself a polar bear, Botts said she swims at the pool at least three times a week practically year round. If the sun is out and the temperature is at least 50 degrees, Botts said she's there.

But, lifeguards at the pool say they have lap swimmers in the 68 degree pool even when the air temperature is below freezing. The pool only closes during thunderstorms or when it's raining so hard lifeguards can't do their job. The pool also closes on Thursdays from 8 a.m. until 7 p.m. so staff and volunteers can clean the pool's slippery rock bottom.

When the "polar bears" finish a swim, they appreciate the warm water in the solar heated showers in the pool's locker rooms. The men's and women's locker rooms are large with several bathroom stalls and a shower for the disabled.

Insider Tips

During the warmer months, swim in the morning hours or at night to avoid the crowds. As an added incentive, admission charges are usually waived at these times. If the algae floating on the water's surface will be a bother, bring snorkeling gear to avoid a faceful of slimy stuff when coming up for air. Also, keep your eyes peeled for other swimmers to avoid collisions.