Nemo 33 is located in Brussels, Belgium and is officially the world's deepest indoor swimming pool, extending a whopping 113 feet beneath the surface. In fact, this pool is so deep, it's actually dark at the bottom! It's temperature is regulated so swimmers don't have to wear wet suits and there are even several underwater caves where divers can explore beyond the main "pit." This footage of Guillaume Néry "playing" at Nemo 33 is mesmerizing. Watch as he floats to its depths in a way that will entrance you as much just as much as it blows your mind. He makes it look easy !!