The Largest Lake In LA County Is An Idyllic Summer Swimming Spot With Family-Friendly Fun

With the summer heat comes the instinct to find the perfect place to cool off. Fortunately for those near Los Angeles County in California, a massive lake is set up for that exact purpose. In fact, with more than 29 miles of shoreline, Castaic Lake is the largest recreational lake in LA County. It offers recreational swimming areas throughout the hottest time of the year, from mid-May to mid-September.

Castaic Lake is actually two bodies of water, which helps divide swimming from other water activities. Only non-powered boaters — canoers, kayakers, and paddleboat enthusiasts, for example — can access the lower lake lagoon where the swimming area is located. Those looking for more active water sports can fully explore the upper lake, which is also stocked with different kinds of fish. Dividing the recreation area into two areas means swimmers of all ages can enjoy the calm water safely, without competing with loud watercraft.

Numerous picnic areas and campsites also dot the shoreline and are a popular way to spend more time on or near the lake's waters. However, as of this writing, Castaic Lake's campsites remain closed until further notice due to damage from the 2025 Hughes fires. Until things are repaired, consider these national parks in California for camping adventures instead. What is open near the swimming area of Castaic Lake is the popular Cali Splash Park. This recreation area boasts more than 50 floating obstacles to tackle, perfect for kids with tons of energy to burn.

Castaic Lake is an ideal swimming lake because its maximum depth in the lower lagoon only reaches about 70 feet. That's much different than the 1,645-foot maximum depth of California's Lake Tahoe, one of the deepest in the United States. Ever since the Castaic Dam was completed in 1974 and formed the Castaic Lake Recreation Area, the lake has been a popular gathering place. And while swimming along the shores of a picturesque California lake is certainly inviting, sometimes you need something a little more exciting. That's why, each summer, Cali Splash Park appears on Castaic Lake. 

Water parks always make a splash, pardon the pun, and are a popular way for tourists to cool off. Every year, when Cali Splash Park opens in late May, the park invites those who meet its requirements to explore a myriad of floating obstacles. It's important to remember, however, that while the park shares the same hours as Castaic Lake's popular swimming areas, there is a separate fee to participate in the splash park's activities.

Castaic Lake Recreation Area is approximately 50 miles north of Los Angeles International Airport (LAX). As of this writing, entry into the area is $12 per vehicle, and swimming is only allowed when lifeguards are on duty during the summer months. The swimming beach is open Wednesdays through Sundays from 10 a.m. to 6 p.m. Kayak, paddleboard, and canoe rentals are available along the lakefront, and rental reservations are recommended, especially during holidays. For more lake swimming across the country, discover the 10 cleanest lakes in the U.S., ideal for taking a dip.