Y-40 "The Deep Joy," the deepest swimming pool in the world, reaches an incredible 42 meters at its deepest points. Located in the Hotel Terme Millepini in Padua, Italy, it was designed by architect Emanuele Boaretto. Because its thermal spring water is kept at temperatures of 90-93°F (32-34°C), divers who visit it don't need to wear wetsuits. Freedivers and scuba divers alike use the pool to practice their diving skills, navigating the pool's various platforms and underwater caves, as well as the shaft that leads to its deepest point. Guests can also walk beneath the pool in a transparent observation tunnel.