The GR 20 is a GR footpath that crosses the Mediterranean island of Corsicarunning approximately north-south, described by the outdoor writer Paddy Dillon as "one of the top trails in the world". The whole trail is about 180 km long with 12,000m of elevation gain, clearly waymarked throughout, the walk for most of the 10,000-20,000 hikers per year takes around 15 days. The trail is considered to be the most difficult of all the GR routes and consists of two parts: the northern part, between Calenzana and Vizzavona and the southern part, between Vizzavona and Conca. Vizzavona is considered the middle as there is a train station, and therefore is an accessible point for walkers beginning or ending a walk consisting of half the route. From Vizzavona, the train can be taken to Bastia or Ajaccio as well as many smaller towns and villages such as Corte. The northern part is considered by some the more difficult part, because of the steep and rocky paths, though this could be an effect of many walkers beginning in the north and not being as fit for this section. The southern part of the trail is often considered easier though the lower altitude may give rise to higher temperatures in summer and so provide more difficult walking conditions. Along the trail there are mountain huts described as "refuges" or gîtes. The standard and price of accommodations and food varies from refuge to refuge. Hikers can sleep in a tent near the refuge, but it is not permitted to pitch tents along the trail. The GR 20 is an advanced trail. Other less difficult trails on the island include the Mare e monti and the Mare a mare trails. The idea of GR 20 comes from a former general inspector for youth and sports, Marcel Schlück, and his friend Guy Degos, both hiking enthusiasts. In June 2016, François D'Haene set the fastest known time in 31 hours and 6 minutes.
Route
Northern part: Calenzana – Ortu di Piobbu or Bonifatu – Carozzu – Asco Stagnu – Tighjettu – Ciottulu di I Mori – Manganu – Petra Piana – L'Onda – Vizzavona
Southern part: Vizzavona – E Capenelle – I Prati – Usciulu – Matalza – Asinao – I Paliri – Conca