With 23 outdoor pools -- not to mention indoor pools, wading pools and spas -- the fact of summer life in Columbia is simple: "The pools are the hubs of the neighborhoods," said Columbia Association aquatics director John Herdson.

The outdoor pools get an average of 600,000 visits a summer. For many of Columbia's 90,000 residents, summer days ebb and flow according to the pool schedule.

For 300 lifeguards, swim instructors and other staff members, the pools offer sun-drenched outdoor work. For everyone else, they provide a respite in the heart of summer. From the minute the gates swing open in the mornings, tots in rubber flip-flops head for swimming lessons or a splash in the baby pools with adults in tow.

Then there are the neighborhood swim leagues with 14 teams in all and hordes of young athletes trying to improve their times. Parent volunteers are busy on the sidelines, organizing and networking, their eyes on the climactic community-wide swim meet July 31.

"The next day, there seems to be an exodus out of Columbia," Herdson said. "Many parents wait until the final swim meet to go out of town."

As afternoons turn into evenings, even the adults might get in a few laps, to say nothing of long chats in the poolside lounge chairs.

"Besides going swimming, you meet neighbors and friends," Herdson said, "and make lasting relationships."

Luka Stone, 3, above, enjoys a splash with his mother, Andrea Stone, at the River Hill pool, one of 23 outdoor pools in Columbia. Below right, Benjamin Germroth, 5, carries boogie boards as he, his mother, Debbie, left, and sister, Alana, 3, join their friends for an afternoon at the River Hill pool. Danielle Eastridge supervises as her 2-year-old daughter, Elisabeth, goes for a dip at the Kendall Ridge pool.Ryan Tiffey takes aim during a game of catch with some friends at the Hawthorn pool in Columbia. The pool offers a variety of activities for all ages, from wading areas for children to adults-only lap lanes. Buoyed by an inflatable float, 6-year-old Kirsten Kruus dips below the surface for a look underwater in the Hawthorn wading pool. Some pools have sand volleyball, a beach and spas. Rosemarie Bond, above, relaxes with a book while sunbathing at the Kendall Ridge pool. Left, lifeguard Kayleigh Brosi keeps an eye on the swimmers at the Hawthorn pool. Each Columbia Association outdoor pool has lounge chairs and umbrellas, a grassy area, baby pool and showers.