Who knows what the first inhabitants of the Grottes de Sare, some 20,000 years ago, would make of today's whiz-bang technology that now lights up the Stygian gloom in these stunning subterranean caves? Multilingual 45-minute tours take you through a gaping entrance via narrow passages to a huge central cavern, where impressive shows of holograms and laser lights are staged.
Follow the D306 6km south of the village of Sare. Hegobus (www.hegobus.com) bus 21 goes from St-Jean de Luz to the caves (€1, four daily).