This massive tropics-themed water park sits about 55 miles northeast of Philadelphia. Just as the adjacent Six Flags Great Adventure theme park is known for big coasters, the 45-acre Six Flags Hurricane Harbor (which is one of several in the country) is popular with water lovers. It features more than 25 thrill slides, including the multilane Big Wave Racer and Tornado, which boasts a 60-foot-wide funnel. Additionally, visitors will find a 1 million-gallon wave pool, a nearly half-mile-long lazy river and the family-friendly Caribbean Cove water playground.