The swimming pools on Wonder of the Seas, which is one of Royal Caribbean’s massive Oasis-class ships, are almost entirely freshwater. In the past, many older cruise ships used filtered and chlorinated seawater, but newer "mega-ships" like the Wonder have transitioned to freshwater systems because they are easier on the skin and eyes, and less corrosive to the ship’s complex plumbing and filtration systems. The ship features several distinct pool areas, including the main pool, the beach pool, and the tranquil Solarium pool for adults. While the main swimming areas are freshwater, the water is still treated with chlorine to maintain strict health and safety standards. However, if you are looking for a "saltwater experience," you can often find it in the ship’s whirlpools or by visiting the nearby ocean at a port of call. It is worth noting that the water in the pools is drained and replaced frequently to ensure it remains pristine for the nearly 7,000 guests the ship can accommodate.