Up your swimming pool game with the Watermelon Ball. We’ll explain. Apparently tossing around a real-life watermelon in water as entertainment is a thing. They behave differently than most air-filled balls, so you can actually dribble, kick, pass, and bounce them—all under water. The reason for this behavior—not floating, not sinking, and sort of suspending itself mid-water—is that watermelons are made of 92% water. That makes them neutrally buoyant. But real watermelons also break and make a mess... The Watermelon Ball is made of tough rubber. You can fill it up with water and just a little bit of air to get it at the right buoyancy. Throw it up to 10 feet under water and combine elements of football, basketball, and rugby for some unconventional aquatic entertainment. Or toss it around outside the water, too. Turns out no part of the pool is off bounds with this summer game changer.