Highly impressive for its "crystal cathedral" of stalactites, this 40m-high cavern comes to life in very professional 40-minute tours whose light shows beautifully illuminate geological formations, while a unique dangling basket (in which you can ride) descends through 'the devil's hole'.
Non-French speakers will find it well worth spending €1 extra for the audioguide. Book ahead in summer. It's 3.5km south of Le Bugue.
