See this article: Swim Center for more detailsEdit
The Swim Center is a building that also becomes available after the "It's All Going Swimmingly" quest. Unlike the home pools, the Swim Center pool is indoors. This pool never requires cleaning, and has diving boards for your Sims. It also includes a toddler clubhouse, a slide, two pool toilets, a kiddie pool, a coffee machine, and a swing set.
Occasionally Wumples can be seen at the Swim Centre.