The Valley of Waves is the central feature of the Lost City at Sun City. It is one of the most advanced water parks in the world, dominated by the Roaring Lagoon, a 6 500-square metre (7560-square yards) wave pool with a palm-fringed beach. Hydraulic mechanisms can generate a 1,8 metre (6 feet 8 inches) wave every 90 seconds. When waves are not generated, a bobbing cycle is generated in a diamond pattern. All Resort residents enter the park free of charge by presenting their resident cards.