Y-40

Y-40 is a purpose-built dive pool at the Hotel Terme Millepini in Montegrotto Terme, in the Euganean Thermal area of the Veneto region. Known as the deepest swimming pool in the world at the time of its construction, it reaches a max depth of around 42 metres and is filled with thermal spring water kept at a warm temperature year round. The facility includes underwater platforms, caves, and transparent tunnels rather than any natural marine environment, making it popular for training, deep certification dives, and freediving practice in controlled, clear conditions. Visibility is generally excellent given the still, filtered water. The site is rated technical given its depth, and access to the deeper sections is restricted accordingly.