A guidebook to trekking the GR20 Corsica, widely considered to be the most difficult of Europe's GR long-distance routes. The 190km (118 mile) trail from Calinzana to Conca traverses the island's mountainous heart and calls for both fitness and experience. Crossing remote and rugged mountainous terrain, there is plenty of hands-on scrambling and, although it is possible to stay under a roof every night, it is recommended that trekkers carry backpacking kit.

The GR20 is presented in 16 stages of 5 to 18km (3–11 miles), with low-level options provided for a number of the stages. It takes around a fortnight to complete. Also included are a handful of excursions to climb neighbouring peaks and link routes for those wishing to join or leave the trail.