I have, Emma.

Just to be clear, though, three distinct trails exist - with rigors specific to each trail...
- GR10: Is probably the trail you mean, and the one I trekked. It is the most popular so offers the most infrastructure: gites and other refuges, friendly towns with places to eat, stores, etc. It also includes the steepest ascents/descents, hard on feet and shins.
- GR11: Is not as 'friendly' as it does not offer as many way-markers, refuges, or towns... You can get lost, I did (but only from the trail, which meant extra mileage that day). You must bring your own camping gear. The GR11 is arguably the most scenically gorgeous, and happens to be less physically demanding than the other two trails.
- HRP: In French, you are trekking au sauvage - camping with few facilities. Infrastructure exists, but the distance to one town from the next means you will camp at least every other night (depending on your pace).

The area is similar to the Dolomites or the Grand Tetons (USA); you know, those jagged spires of rock that are insanely gorgeous. Except now you are trekking them, up and down, up and down, up and down. (Especially on the GR10.) Be prepared: proper shoes are mandatory due to the long distances, difficult terrain, and possibly carrying camping equipment. And s t r e t c h your shins for weeks before going. You will be thankful while you walk. Trust me! :-)

All of these trails run from the Atlantic to the Mediterranean. The distance for the entire trail runs, if I recall correctly, ~550 miles. Because of the constant up and down, you must factor a much slower pace and thus duration to trek the entire trail. I would estimate 50 days. (A widely accepted calculation: ~10-11 miles/day.) Weather is another factor that will slow you down; it is not always good, especially on the GR10.

A trekker could do all of the trail, or some of it. Yes, you can do the trail, if you are hardy and tenacious, disciplined, and prepared. I met a fellow on the trail from England; he was, at that time, 74. If he can do it...

Another distance trek in propinquity (you could begin in San Sebastian) is the Camino de Santiago. From beginning to end requires ~30 days, is difficult but not as strenuous, is insanely gorgeous, you travel through many cute towns, and offers a spiritual component. (I shared my experiences re this trail elsewhere on AFAR.)

Please feel welcome to write privately for more info.

Posted Jun 24, 2012