Nemo 33 is an indoor swimming pool that was constructed in Uccle, Belgium during 2004. Nemo 33 has the honor of being the deepest indoor swimming pool in the entire world. The deepest parts of the pool descend over one hundred feet into the ground. The water is kept at a very warm temperature at all times. Nemo 33 also has simulated caves for divers and swimmers to explore while enjoying the warm waters.