REDONDO BEACH - Seaside Lagoon Water Park. The large saltwater lagoon with chlorinated water  offers trained lifeguard supervision. Besides swimming, the Lagoon offers a large sand area for sunbathing, children's play equipment, and volleyball courts. There is also a grassy area and luau shelter for day and evening events, plus snack bar facilities provided by Ruby's Restaurant onsite. Time: 10 a.m. to 5:45 p.m. daily. Cost: $5 adult; $4 child; Free under 2 years. Season pass family of 4 is $100. Call: (310) 318-0681. redondo.org