Grottes de Bétharram is a network of subterranean caverns that has been carved out from the limestone, glittering with impressive formations of stalactites and stalagmites. Visits to the cave aboard a combination of foot, minitrain and barge last around 1½ hours, but be warned: the site gets extremely busy in high summer. It's along the D937, 14km west of Lourdes.
It's also possible to visit between February and late March at 2pm and 4pm Monday to Thursday, and at 2pm on Friday.
