Not in OC, but close to the northern cities near the 57.
"Raging Waters, California's Largest Waterpark , ranked #3 nationally by the Travel Channel in its Top 10 ranking of US Water Parks, invites you to participate in “The Summer of the Dragon!”
With over 50 beautifully landscaped acres and 36 slides and attractions, plus a sand beach, there is outRAGEous fun for guests of all ages. Experience the Dragon's Den, Raging Waters newest attraction, twist down the 10-story High Extreme, float down the ¼ mile Amazon River or relax in the huge Wave Pool. Younger guests will never tire of Kids' Kingdom and Splash Island. Whether mild, wild or in-between, all ages always have a raging good time at Raging Waters San Dimas."