GR 10
GR 10 (also marked GR10) is the French long-distance hiking route that traverses the Pyrenees from Hendaye on the Atlantic coast to Banyuls-sur-Mer on the Mediterranean side. The route is designed as a continuous, multi-day footpath for hikers planning the whole crossing or tackling it in staged sections.
The full traverse is about 866 km end-to-end, with roughly 48,000 m of ascent and a similar amount of descent. The overall effort is mountain trekking rather than technical climbing, but the route includes stretches with substantial one-day vertical gain and long days typical of GR footpaths.
Navigation is built around the standard GR waymarking: red-and-white blazes painted on rocks, trees, and poles. Expect route changes around towns and villages, so carrying newer map/guide editions helps when you’re planning stages.
Lodging and resupply are oriented to walkers. Along the way you’ll typically find gîtes d’étape, basic mountain refuges, and municipal camping options; camping is mainly needed only for limited nights in the Ariège section when you’re not using lodging.
Typical completion time for fit hikers is on the order of 45–60 days, but many people split the crossing over multiple visits. West-to-east travel is commonly chosen to follow the cooler, greener Basque start and then move toward the higher, more rugged terrain closer to the Mediterranean.
Season matters on a high-latitude, high-elevation route like this. Best hiking conditions are generally late spring to early summer and late summer to early fall; mid-summer heat can be an issue, while winter conditions are usually dominated by snow. Storms become more frequent in fall.
The GR 10 runs through several French departments in the Pyrenees chain—Pyrénées-Atlantiques, Hautes-Pyrénées, Haute-Garonne, Ariège, and Pyrénées-Orientales—so stage planning can be done with geography in mind (Basque start, then deeper Pyrenean valleys and passes, ending toward the Mediterranean coast).
More information: Wikipedia, Hiking on the GR10 ! - Guide du Pays Basque, GR 10 | Hendaye | France - Hiiker