The GR20 in Corsica covers 180 km of granite ridges from Calenzana in the north to Conca in the south, split into 15 stages with roughly 12,000 m of total elevation gain. It is Europe's most technically demanding long-distance trail and requires proven multi-day mountain experience before you attempt it.
Why the GR20 Earned the Title of Europe's Toughest Long-Distance Trail
The GR20 (Grande Randonnée 20) was rated Europe's hardest trail by outdoor magazine consensus long before its current visibility on YouTube and social media. Unlike the Tour du Mont Blanc or the Camino de Santiago, the GR20 does not follow valley paths — it stays high, often above 2,000 m, scrambling over polished granite slabs with fixed chains on the most exposed sections.
The 2015 rockfall in the Cirque de la Solitude permanently rerouted Stages 5 and 6 around the canyon rather than through it. The new variant adds distance but eliminates the fixed-chain rappel that killed three hikers in that incident. As of 2026, the official GR20 route follows this safer alternative and is clearly signposted from the Refuge de Ciottolu di i Mori.
GR20 Route Overview: North to South in 15 Stages
The standard north-to-south direction is recommended because prevailing Corsican wind blows from the north, keeping it at your back rather than in your face. Most hikers complete the route in 14 to 16 days depending on pace and weather delays. The northern half (Stages 1–7) is significantly harder than the southern half, with more scrambling, higher passes and fewer bailout options.
Stage start and end points are all served by mountain refuges (bergeries) operated by the PNRC (Parc Naturel Régional de Corse). Booking is mandatory in peak season (July–August) and opens in March each year through the PNRC website. Refuge prices run €10–€15 per night for a camping pitch and €22–€30 for a dormitory bunk.
Stage-by-Stage Key Facts: Distance, Ascent and Difficulty
| Stage | From → To | Distance | Ascent | Walking Time |
|---|---|---|---|---|
| 1 | Calenzana → Ortu di u Piobbu | 12 km | +1,550 m | 7h |
| 2 | Ortu di u Piobbu → Carrozzu | 8 km | +750 m / −1,050 m | 6h30 |
| 4 | Asco Stagnu → Bergeries de Ballone | 9 km | +1,250 m / −1,230 m | 9h30 |
| 9 | Vizzavona → Bergeries de Capanelle | 14 km | +1,100 m | 5h |
| 15 | Paliri → Conca | 13 km | +250 m / −1,270 m | 5h |
What Gear to Pack for the GR20
The GR20 punishes heavy packs. Granite slab scrambling, chain-assisted ascents and steep descents demand both stability and lightness from your kit. An ideal base weight for the GR20 is under 7 kg, with a total pack weight including food and water not exceeding 11–12 kg.
Shelter is the most critical gear decision. The PNRC campsites require you to carry your own tent for overnight stays between refuges. The MSR Carbon Reflex 1 (745 g) is purpose-built for exactly this use: ultralight single-wall construction that pitches fast in the exposed col locations typical of GR20 campsites. The Corsican mountains experience sudden thunderstorms from May to September, so storm-rated shelter performance is non-negotiable.
Mountain weather on the GR20 changes within two hours. You can leave a refuge in sunshine and reach a col in fog and horizontal rain before noon. The Arc'teryx Alpha SL Jacket (227 g) packs to fist-size and provides full waterproofing without the bulk of a three-layer shell — keep it accessible at the top of your pack, not buried inside. Safety communication is equally essential on the northern stages where mobile network coverage drops to zero. The Garmin inReach Mini 2 (100 g) allows two-way text messaging and SOS via the Iridium satellite network regardless of mobile signal. On Stage 4's nine-hour push over the Col Perdu at 2,183 m, having that fallback is basic mountain sense.
For pack selection on a 15-day route, the best ultralight backpacks for thru-hiking in 2026 guide covers volume and suspension requirements specifically for trips of this length.
Best Time to Hike the GR20 and How to Book Refuges
The official hiking season runs from mid-June to late September. July and August are peak season: refuges book out within days of the March opening and trail sections above 2,000 m see 200+ hikers daily, creating bottlenecks at fixed-chain passages.
The best windows are late June or the first three weeks of September. Snow has cleared the high cols by late June and September brings stable high pressure, emptier refuges and lower nightly rates. Early October is possible on the southern half but the northern stages become genuinely hazardous once first snowfall arrives, typically from mid-October. Booking opens 1 March each year through the PNRC reservation system — secure all nights simultaneously on opening day for a July or August trip.
What to Expect: Weather, Water and Terrain
Water sources are plentiful from June to August, with snowmelt feeding streams and refuge water points on almost every stage. By late September, some high-altitude sources dry out. The most dangerous weather pattern is the Corsican thunderstorm cycle: clear mornings followed by convective storms from 13:00 to 17:00, most common in July and August. Starting each stage by 07:00 and reaching the next refuge before midday is standard practice among experienced GR20 hikers.
The GR20's granite is some of the most beautiful in Europe but also among the most unforgiving: wet polished slabs are extremely slippery, and ankle rolls on loose stone are the most common trail injury. Poles add critical stability on descents — see the best trekking poles of 2026 for recommendations suited to a technical alpine route. For difficulty context, the Tour du Mont Blanc guide covers what separates a beginner-accessible trail from one that demands genuine alpine experience. Current stage maps and refuge status are published by le-gr20.fr, the authoritative source for 2026 trail conditions.
Frequently Asked Questions
How fit do you need to be to hike the GR20?
You need to sustain 6–9 hours of hiking with a 10–12 kg pack on consecutive days, including terrain with 1,200 m of daily elevation gain. Previous experience on multi-day alpine routes — at minimum two or three separate three-day mountain trips — is the recommended baseline. The GR20 is not a suitable first backpacking trip.
Do I need to book GR20 refuges in advance?
Yes, especially for July and August. Booking opens 1 March each year through the PNRC reservation system. Camping pitches at each refuge offer more flexibility than dormitory beds since capacity is higher. In September, two to three weeks' advance booking is generally sufficient for most stages.
Can you hike the GR20 without a tent?
Yes, but only if you pre-book dormitory beds at every refuge. During peak season, dormitories fill completely before arrival for walkers without reservations. Carrying a lightweight tent gives flexibility when weather delays push you off schedule by a full stage — which happens regularly on the northern half.
How long does it take to complete the GR20?
The standard completion time is 14–16 days for hikers of average fitness. Faster hikers complete it in 10–12 days; the current FKT is under 32 hours by elite trail runners. Planning 15 days gives one buffer day for weather or injury without needing to shorten any stage.
Is the GR20 harder than the Tour du Mont Blanc?
Yes, significantly. The TMB follows well-maintained valley paths with consistent waymarking and escape routes at every stage. The GR20 involves genuine scrambling with fixed chains, higher average altitude, more technical terrain and longer stages with fewer bailout options. Most hikers who have done both rate the GR20 as substantially harder.