Cull Canyon Regional Recreational Area is located in Castro Valley, California. The park is spread over 290 acres and offers a variety of recreational activities such as hiking, picnicking, fishing, and swimming. The park has a man-made lake with a swimming lagoon that is open during the summer months. The park also has several hiking trails that offer scenic views of the surrounding hills.

One of the main attractions of Cull Canyon Regional Recreational Area is its swimming lagoon, which is a great place to cool off during the summer months. The park also has several picnic areas that are perfect for spending a day with family and friends. Fishing is another popular activity at the park, with the lake stocked with catfish, bass, and trout.

The park has an interesting history, having been used by the Ohlone people for thousands of years before the arrival of European settlers. The park was also used as a movie set for several Hollywood productions, including the 1941 film "Sergeant York."

The best time of year to visit Cull Canyon Regional Recreational Area is during the spring and summer months, when the weather is warm and the park's facilities are fully open. The park is open from 8 am to sunset and has an entrance fee of $5 per vehicle.

In summary, Cull Canyon Regional Recreational Area offers a variety of recreational activities, including swimming, picnicking, and fishing. The park has an interesting history and is a great place to spend a day with family and friends. The best time of year to visit is during the spring and summer months.