Biarritz - Europe's historic surfing capital (blessed by powerful waves), seawater therapy, fitness and health center of Europe, favorite destination for Napoleon III and Russian Czar family. It lies between the sea and the mountains and a stone's throw away from Spain.
Visit the Sea museum (musée de la mer) which has a shark tank with panoramic windows and don't forget to bring some food - seals (no food for sharks!) are always hungry. It's allowed to take pictures but without flash. The Chocolate museum (musée chocolat) is a must-see for people who have a sweet tooth.
The Virgin Rock (with statue of the Virgin Mary on its peak) is very beautiful at sunset (the rock is connected to the land by a metal footbridge).
Opposite the stately Hôtel du Palais is Ēglise Alexandre Newsky, a Russian Orthodox church constructed by and for the Russian aristocrats who frequented Biarritz until the Soviet Revolution in 1917. Don't be surprised to see Chinese looking priest who speaks Russian without accent!
Using a bullet-train you can easily reach probably the most venerable place (for Catholics) on Earth - Lourdes. In this place in 1858 the 14 years old girl saw the Virgin Mary in a series of 18 visions (This girl, Bernadette, was canonized in 1933). I'd emphasize (as an Orthodox believer) such a familiar for every Catholic thing as 14 stations of the Cross. In Lourdes you have to walk through those stations for up to 1,5 km and all statues (notably of the Christ and His followers) are life-size figures! Great experience!
To climb a mountain take a bus to St. Jean de Luz (lovely medieval city) and then inland to the La Rhune (905 m.) There is a hiking path from the train station up to the summit (2h.30 up and 2h down) or you can take the "Petit Train de la Rhune" (travelling time - 30 min., cost - 13 euro). You can see wild cows, pottoks - wild horses (Basque donkeys) or even vultures if you are lucky enough. Just remember to wrap up as temperature drops significantly going up there.
Fancy good paella? No problem, just head West to San Sebastian across the Spanish border (21 km from Saint Jean de Luz). You won't need any ID card to get to Spain!
Back to France try Izazza - sweet liqueur made with herbs collected from the Basque mountains. Yellow Izazza is made with 32 herbs and is 40 proof but green Izazza is made with 48 herbs and is 48 proof! Cheers!