The Carmel Valley Recreation Center is a huge outdoor/indoor sports complex operated by the City of San Diego. Here you can find a place to do just about anything physical that you're interested in, including baseball, softball, basketball, tennis, horse shoes, football, shuffle board, soccer, and swimming at an Olympic-size swimming pool. Also on its ground is a large outdoor amphitheater used for various local concerts and stage productions.
The pool offers swimming lessons, youth water polo, and recreational swim. Hours for family swim are subject to change, so call before you go.