Sesame Place San Diego is a family theme and water park in Chula Vista, aimed squarely at younger children with Sesame Street characters, rides and splash attractions. It is one of the clearest kid-focused day trips in the South Bay.
The park is seasonal in parts and strongly weather-dependent, so check operating calendars before promising a visit. For families staying in Chula Vista, it can be a full day; for adult travelers, it is easy to skip.