Shadow Cliffs Regional Recreation Area is a regional park on the border of Pleasanton and Livermore, California, that is part of the East Bay Regional Parks system. Its lake, once a gravel pit, has a sandy beach and is used for swimming, fishing, and recreational boating. The park once featured water slides, which were closed in 2011 and have since been taken down, and are planned to be replaced by an Interpretive Center. The park is also a popular picnic ground.