France: Gouffre de Padirac
If natural attractions is what you are after, Gouffre de Padirac should be on the top of your list. Gouffre de Padirac aka Padirac Chasm is a massive vertical sinkhole (like the Cave of Swallows in Mexico), 103 m / 338 ft deep and 33 m/ 108 ft in diameter. Once you descend down via a staircase, you got a spectacular cave to explore with a boat ride in an underwater lake. The cave was first explored in 1889 and opened to tourists a decade later. The underground tour leads through a series of very decorated halls – Salle du Lac de la Pluie (Rain Lake), pendant-like Pendeloque (Giant Stalactite), Salle des Grands Gours, and then Salle du Grand Dôme with an impressive 94 m-high ceiling. One of the most impressive caves in the world (and I’ve been to a lot) – an absolute top 10!