Students swim during an apnea course by Italian free diver, Umberto Pelizzari, at the “Y-40 The Deep Joy” swimming pool on December 8, 2014 in Montegrotto Terme, northeastern Italy. The swimming pool is built over thermal sources bringing after cooling down a water at 32-34 degrees Celsius. Y-40, with its depth of 42mt, is officially included in the Guinness World Record as the deepest pool in the world for free and scuba diving. AFP PHOTO / OLIVIER MORIN