About the GR10
From Wikipedia: “GR 10 is a French GR footpath, or hiking trail, that runs the length of the Pyrenees Mountains. It roughly parallels the French–Spanish border on the French side. Those attempting the entire trail often choose to walk it from west to east, from Hendaye on the Bay of Biscay to Banyuls-sur-Mer on the Mediterranean Sea, but it can also be traversed east to west.
Hiking the entire route is estimated to take around 52 days for hikers who are physically fit and used to mountain hiking. Some stretches involve a lot of ascending and descending, including a few one-day sections that can climb and then descend 1,200 metres (3,900 ft), but the GR 10 is a hiking trail, and there is no actual mountain climbing involved. The trail covers a distance of 866 kilometres (depending on alternatives taken), with 48,000 metres (157,000 ft) of ascent and, given the coast-to-coast nature of the route, the same descent.”
Some websites
gr10.org (French)