Yes, swimming is a very popular activity in the Delaware Water Gap National Recreation Area, but it is restricted to specific areas for safety. The two primary lifeguarded beaches are Smithfield Beach (in Pennsylvania) and Turtle Beach (in New Jersey), which are typically open from mid-June through Labor Day. There is a small "expanded amenity fee" (usually around $10 per vehicle) to park at these beaches during the summer. While you are technically allowed to swim in other parts of the river, it is strongly discouraged and can be very dangerous due to strong currents, sudden drop-offs, and hidden underwater debris. The Delaware River may look calm on the surface, but it is a powerful moving body of water. Wearing a life jacket (PFD) is highly recommended for all swimmers, even at the designated beaches. Diving from cliffs or rocks is strictly prohibited throughout the park. For those who prefer calmer water, many visitors also enjoy wading and swimming in the various creeks and at the base of smaller waterfalls like Milford Beach, though these areas are not lifeguarded and require extra caution.