GR 20 Principale

The GR 20 Principale is a 180-km point-to-point trail across the mountainous spine of Corsica, France, gaining roughly 12,000 m of elevation over about 15 days. Rated the most difficult of all France's GR routes, it links Calenzana in the northwest with Conca in the southeast, crossing granite ridges, glacial lakes and high passes above 2,000 m.

About the GR 20 Principale

The GR 20 — known locally as Fra li Monti ("between the mountains") — runs the full length of Corsica's central watershed, the rocky backbone that splits the French Mediterranean island in two. At 180 km with around 12,000 m of cumulative ascent, it is widely described as the toughest of France's Grande Randonnée network and one of the hardest waymarked treks in Europe. Between 10,000 and 20,000 hikers attempt it each year, and the outdoor writer Paddy Dillon has called it "one of the top trails in the world."

The route was laid out in 1972 by Michel Fabrikant, with Marcel Schlück and Guy Degos credited as originators, and is maintained by the Parc naturel régional de Corse (PNRC), which runs the chain of mountain refuges along the way. It is marked throughout with the familiar red-and-white painted flashes used on every GR path in France.

The trail splits naturally at the village of Vizzavona into two contrasting halves. The northern section (Calenzana to Vizzavona) is the harder, higher and more spectacular part: sharp granite, scrambling, ladders, chains and exposed ridgelines beneath peaks such as Monte Cinto (2,706 m), the highest mountain in Corsica. The southern section (Vizzavona to Conca) is gentler underfoot, with grassy bergerie pastures, pine forest and the dramatic granite spires of the Aiguilles de Bavella, before the path drops to the coastal village of Conca near Porto-Vecchio.

This is not a stroll. Daily stages average five to seven hours of demanding walking, with hands-on scrambling on the northern half, large rough boulders, and long sustained climbs and descents. Fitness, sure footing and a head for some exposure are essential. Hikers seeking a gentler high-mountain crossing often warm up on something like the Theth to Valbona trail in Albania before committing to a full GR 20.

Route Overview & Stages

The GR 20 is traditionally walked north to south in 15 to 16 stages, each ending at a PNRC refuge. The breakdown below follows the classic itinerary; distances are short but slow, because the terrain — not the kilometres — sets the pace.

Strong, experienced walkers sometimes compress the route into 11 or 12 days by combining stages; most people are glad of the full 15 to 16. The two-week northern-and-southern combination is the standard end-to-end thru-hike.

Highlights & Points of Interest

• Monte Cinto (2,706 m) — Corsica's highest summit, skirted on the high variant near the Pointe des Éboulis (2,607 m), the loftiest point the trail itself touches.
• Cirque de la Solitude — the legendary chained gully between Ascu Stagnu and Tighjettu, closed after a fatal rockfall in June 2015 and replaced by the Monte Cinto high route, now the route's defining challenge.
• Lac de Nino — a glacial lake ringed by spongy pozzines grasslands where semi-wild horses, cattle and pigs graze, at roughly 1,760 m.
• Brèche de Capitello & Lac de Capitello — one of the most photographed spots on the trail, a deep turquoise lake below the granite breach above the Restonica valley.
• Spasimata slabs & suspension bridge — polished granite ramps fitted with fixed chains, and a swaying footbridge over the Carozzu stream.
• Aiguilles de Bavella — the saw-toothed granite needles above the Col de Bavella, a climbing and scrambling playground at the southern end.
• Monte Incudine (2,134 m) — the highest peak of the southern half, with long views toward the Tyrrhenian Sea.
• Vizzavona — the forested halfway hamlet with a railway station, the natural place to start, finish or split a trip.

Best Time to Hike the GR 20 Principale

The realistic hiking window is mid-June to late September, when the refuges are staffed and most snow has melted from the high passes. Outside this period the route is a serious mountaineering undertaking: snowfields linger on north-facing slopes into early summer, and storms can arrive without warning.

June brings long daylight, wildflowers and snowmelt-fed lakes, but residual snow can block the highest sections of the northern half and ice axes are occasionally needed early in the month. July and August are the warmest and most reliable, yet also the busiest — refuges and camping pitches fill quickly, and afternoon thunderstorms build over the ridges, so early starts are vital. September offers cooler, more stable air, thinner crowds and clearer light.

The single best month to hike the GR 20 is September: snow has long gone, the fierce summer heat has eased, thunderstorm frequency drops and the trail is markedly quieter than in the July–August peak. For 2026, aim for the first three weeks of September before refuges begin winding down their staffed season toward the end of the month. Whatever month you choose, check the PNRC and Météo-France bulletins the night before each high stage, as conditions above 2,000 m change fast.

Practical Information

Accommodation

Accommodation along the GR 20 is built around the network of 16 PNRC mountain refuges, spaced roughly a day's walk apart. Each offers a bunk in a dormitory (around €14 per person), space to pitch your own tent on the refuge platform (around €7–9 per person), or rental of a pre-pitched tent. Some refuges and the valley bergeries and gîtes near Asco, Castel de Vergio, Vizzavona, E Capannelle and Bavella offer half-board (dinner, bed and breakfast) for roughly €45–55. Refuges sell basic supplies — pasta, cheese, charcuterie, beer and sometimes hot meals — but ranges are limited and prices high, so plan resupply carefully. Bunks and meals should be reserved in advance through the official PNRC online system, as walk-up beds are not guaranteed in peak season; campers generally pay on arrival.

Getting There & Back

The northern trailhead at Calenzana is reached from Calvi, whose airport (Calvi–Sainte-Catherine) and port handle seasonal flights and ferries from mainland France. A shuttle bus or taxi covers the 15 km from Calvi to Calenzana in about 25–30 minutes. Bastia, around two hours away by road and rail, is the other main air and ferry gateway. The southern finish at Conca is served by a seasonal navette to Sainte-Lucie-de-Porto-Vecchio (about 20 minutes), from where buses run to Porto-Vecchio and Bastia. Midway, Vizzavona sits directly on the Ajaccio–Bastia railway line, making it easy to start, exit or rejoin the trail by train.

Permits & Fees

No permit or entry fee is required to walk the GR 20; the path crosses the Parc naturel régional de Corse, which is freely accessible. Your only mandatory costs are refuge bunks or camping pitches (paid per night) and any meals or supplies you buy en route. Wild camping is officially prohibited outside the designated refuge areas, and lighting fires is banned given the extreme summer wildfire risk. Budget roughly €20–35 per day if camping and self-catering, or €50–70 per day with refuge half-board.

Gear & Packing List

The GR 20 rewards a light, well-organised pack — you carry it up 12,000 m of ascent, much of it hand-over-hand on rock. A capacity of 40–55 litres is plenty for a self-sufficient summer crossing with a tent and a few days of food. The Arc Haul Ultra 60L suits campers carrying a tent and full resupply, while the 2400 Windrider is a durable mid-size choice for refuge-based hikers travelling lighter. If you prefer a more structured load-hauler, the Aircontact Lite 45+10 carries heavier resupplies comfortably. Compare options in our roundup of the best ultralight backpacks of 2026.

Essentials include sturdy approach shoes or B1 trekking boots with grippy soles, trekking poles for the relentless descents, a 2–3 litre water capacity, sun protection for the exposed ridges, and warm and waterproof layers for sudden storms above 2,000 m. Because daily effort is so high, calorie planning matters — see how much you should eat in our guide to how many calories you need hiking a full day — and carry lightweight, energy-dense food between refuge resupplies.

Similar Trails You Might Like

If the GR 20's alpine character appeals, two other multi-day European classics make natural follow-ups. The first circles the highest massif in the Alps; the second traces a historic Waldensian pilgrimage route through the French and Italian mountains. Explore the Tour du Mont Blanc - Itinéraire principal for a celebrated high-mountain loop, or the 325 km Sulle strade dei valdesi: GRV Glorioso Rimpatrio dei Valdesi for a longer, history-rich traverse.

Frequently Asked Questions

When is the best time to hike the GR 20?
Mid-June to late September is the staffed-refuge season. September is the single best month: high-altitude snow has melted, summer heat and thunderstorms ease, and crowds thin out compared with the July–August peak. June is beautiful but can still hold snow on the northern high passes, sometimes requiring an ice axe.

How difficult is the GR 20?
It is rated the hardest of all France's GR routes and one of the toughest waymarked treks in Europe. Expect hands-on scrambling, fixed chains, ladders, big rough boulders and exposed ridges, especially on the northern half. Good fitness, sure footing and a head for moderate exposure are essential; technical climbing skills are not.

How long does each day's stage take?
Daily stages are short in distance — typically 6 to 17 km — but slow, averaging five to seven hours of walking because of the rocky, steep terrain. The full 180 km route is usually completed in 15 to 16 stages, though strong hikers compress it into 11 or 12 days by combining sections.

Where do you sleep on the GR 20?
You stay at a chain of 16 PNRC mountain refuges spaced about a day apart. Each offers dormitory bunks (around €14), tent pitches (around €7–9) or pre-pitched tent rental, and some provide half-board near €45–55. Reserve bunks and meals in advance through the official PNRC system, as walk-up beds sell out in summer.

Do you need a permit to hike the GR 20?
No permit or entry fee is required; the trail crosses the freely accessible Parc naturel régional de Corse. You only pay for refuge bunks, camping pitches and any food bought en route. Wild camping outside refuge areas and lighting fires are both prohibited, mainly because of the severe summer wildfire risk.

For official refuge bookings, trail status and safety bulletins, consult the Parc naturel régional de Corse, and for general GR waymarking standards and route updates see the Fédération Française de la Randonnée Pédestre.