GR20
Frà li monti
OSM hiking route on Corsica's granite spine (183.6 km line), Calenzana to Conca. Vertical figures sampled from Copernicus GLO-30. Days (15) is a placeholder from round(lengthKm/12), not the published 14–16 day window (unverified).
Last verified 2026-09-24 vs Parc naturel régional de Corse
Cite this record
The Hiking World, GR20, verified 2026-09-24, https://www.thehikingworld.com/trails/gr20
How we verify · last checked 2026-09-24
Byline
- The Hiking World editorial · author
Desk byline for seed records. Named surveying editors replace this once a trail is verified.
Figures marked provisional are seed data and still need verification. Source and last-checked date sit under each cited value.
Weather forecast
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Permits and fees
| Permit | Cost | Quota / restriction | Issuer | Source | Verified |
|---|---|---|---|---|---|
| No walking permitUnverified — not officially sourced | Not recorded | — | Parc naturel régional de Corse | Issuer page | Unverified |
Hut reality check
Full sleeping bag — blankets are not provided
PNRC refuges: you must carry your own duvet/sleeping bag; park tents include a mattress, not blankets.
Staffed-season refuges offer evening meal, breakfast, and a packed lunch; grocery at each refuge. Overnight is lodging logistics, not a walking permit.
PNRC beds, bat-flancs, and tent pitches are booked on the park system. See the hut-to-hut booking guide. How hut-to-hut booking works.
pnr.corsica · verified 2026-09-10Gear mandates
PNRC “fond de sac obligatoire”: duvet, rain jacket (or equivalent), warm layer, trousers, first-aid, survival blanket, towel, mountain shoes, cap, shorts, headlamp, filter bottle and purification tablets, and the FFRP topo-guide (ref. 067). That is the park list, not a desk packing opinion. Fees are not copied.
pnr.corsica · verified 2026-09-10
Official mandate only — not a packing-list opinion.
Local ethics / Leave No Trace
Wild camping is prohibited; camping only next to refuges or on marked bivouac areas (municipal orders on the PNRC GR20 page).
pnr.corsica · verified 2026-08-24Smoking and fires banned in forests 15 June–30 September. From mid-June to mid-September massifs can close with the weather; no GR20 departure from Calenzana after 11:00.
pnr.corsica · verified 2026-08-24
Altitude weather delta
High 2,589 m minus low 254 m is 2,335 m of relief on this record. A standard tropospheric lapse of 6.5 °C per 1,000 m implies about 15.2 °C cooler at the high point than the valley, all else equal.
That is a model (International Standard Atmosphere environmental lapse), not a forecast and not a trail-closure. Wind, snow, and storms stay in Hazards.
derived:lapse-rate · verified 2026-09-10 · provisionalISA 6.5 °C / 1,000 m · wikipedia.org · 2026-09-10
Line download is the stored OSM geometry, simplified. It is not a surveyed GPS track. GPX · GeoJSON
Editorial v1 · Provisional catalog
North very technical; south easier
- SAC T2–T4 (mapped — no official SAC grade)
- Mountain hiking. Continuous trail, some steep ground, sure-footedness helpful. through Alpine hiking. Sometimes pathless; exposure and simple climbing terrain.
- YDS Class 1
- Class 1. Walking on an established path; low fall risk.
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Ingested from OpenStreetMap relation 12484370 (ODbL). The mapped line and 2D length are derived from that geometry. Ascent, descent, and high/low points are sampled from Copernicus GLO-30 (copernicus-dem:glo-30) and remain provisional. Water, permits, and hazards were not taken from OSM tags and must be verified.
OSM 2D length is 183.6 km (relation 12484370; GR 20 Principale, red/white nwn, Wikidata Q262374). Endpoints are Calenzana (fontaine San'Antone / OSM line start) to Conca. Yellow-dot difficult variants are separate OSM relations (1771390 Monte Incudine; 9627013 Variante Alpine Onda–Vizzavona) and were not fetched. lengthKm is verified: 183.6 km is within ~3% of PNRC/FFRP ~180 km (independent published figure; variants excluded; https://www.pnr.corsica/fr/randonnees-decouverte/gr-20-fra-li-monti, checked 2026-08-24). Published 14–16 days remain a window, not a DataPoint. Wikipedia GR 20 infobox 180 km (https://en.wikipedia.org/wiki/GR_20, checked 2026-08-24, CC BY-SA) stays in the published band.
DEM high 2,589 m sits in the published high-pass band (~2,000–2,600 m). GLO-30 cumulative ascent 12,361 m is in the same order as Wikipedia's 12,000 m gain (same page, checked 2026-08-24); a ~28,000 m published lead is a cross-check only and is not this DataPoint. High point left as Copernicus.
typicalDays 16 is the published typical thru-hike (PNRC Frà li monti / refuge booking, https://www.pnr.corsica/fr/randonnees-decouverte/gr-20-fra-li-monti, checked 2026-08-24). Published window 14–16 days; not a DataPoint. Refuge-warden season 16 May–4 Oct 2026; practical walking is late June–September (same PNRC page; pnr-resa.corsica booking calendar).
Water was not mapped to named WaterSource points (no honest atFraction). PNRC notes refuge running water and stage springs; they were not positioned from an official named list this pass.
Water security
Sourced carry / availability
PNRC lists running water and stage springs at refuges; they are not mapped as named WaterSource points on this record. The park’s mandatory kit includes a filter bottle and purification tablets. Carry capacity in litres is not copied from unofficial lists.
pnr.corsica · verified 2026-09-10Surface
Surface is not recorded. This field is filled only from an OSM surface tag, not from the grade.
Permits & fees
No permit required.
Getting there
Sourced legs to the Calenzana (OSM line start) base start station — where this trail record begins. This is not a route planner: durations are approximate and marked provisional until an official transport page confirms them.
Road · Calvi Sainte-Catherine (CLY) → Calvi
Calvi airport is the closest air gateway to the GR20 northern trailhead (https://en.wikipedia.org/wiki/Calvi_%E2%80%93_Sainte-Catherine_Airport, checked 2026-08-24).
en.wikipedia.org · verified 2026-08-24 · wikidata · official · provisionalRail · Bastia Poretta (BIA) → Calvi
Bastia is the other advertised Corsican gateway (https://en.wikipedia.org/wiki/Bastia_%E2%80%93_Poretta_Airport, checked 2026-08-24). Continue to Calvi by the island railway or bus, then road to Calenzana.
en.wikipedia.org · verified 2026-08-24 · wikidata · official · provisionalRoad · Calvi → Calenzana
PNRC: the GR20 starts in Calenzana at the fontaine de San'Antone (https://www.pnr.corsica/fr/randonnees-decouverte/gr-20-fra-li-monti, checked 2026-08-24). Local bus or taxi from Calvi; no rail to the village.
pnr.corsica · verified 2026-08-24 · official · provisional
No rail to Calenzana. PNRC forbids GR20 departures from Calenzana after 11:00 in the fire-risk season (checked 2026-08-24).
Plan from your location
Type a city, then pick a match. These links open external search tools — they do not fetch fares or timetables.
Getting there car-free
Calenzana (OSM line start) · car-free flag: unknown
PNRC: the itinerary begins in the upper village at the fontaine de San'Antone (https://www.pnr.corsica/fr/randonnees-decouverte/gr-20-fra-li-monti, checked 2026-08-24). No GR20 departures from Calenzana are allowed after 11:00 (same page, fire-risk rule).
Conca (OSM line end) · car-free flag: unknown
PNRC stage 16 ends at Conca; a demand shuttle toward Santa Lucia di Portivechju / Porto-Vecchio is listed on that page (checked 2026-08-24).
Trailheads
- Calenzana (OSM line start) car-free: unknown
- Conca (OSM line end) car-free: unknown
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Hazards
- The north (Calenzana–Vizzavona) is the hard end: PNRC describes those stages as very technical, with steep, narrow, and slippery ground, rock slabs with handrails on alpine variants, scree, and in places rappel descents; hands may be needed from stage 1. This is scramble terrain, not glacier or T5/T6 climbing (https://www.pnr.corsica/fr/randonnees-decouverte/gr-20-fra-li-monti, checked 2026-08-24).
- Rapid mountain weather including violent summer thunderstorms (PNRC mountain-safety notes, same page, checked 2026-08-24).
- The Cirque de la Solitude / E Cascettoni is closed after the 10 June 2015 rockfall; the official GR20 uses the FFRP diversion (same page, checked 2026-08-24).
Questions
Do I need a permit for GR20?
No trail permit is listed as required on this record for GR20.
When is the best time to hike GR20?
On this record the best season is: Refuge season 16 May–4 Oct 2026; practical late Jun–Sep.
How difficult is GR20?
GR20 is graded PNRC: one of Europe's most difficult; N très technique · SAC T2–T4 (mapped — no official SAC grade) · YDS 1. A sourced hazard on this record: The north (Calenzana–Vizzavona) is the hard end: PNRC describes those stages as very technical, with steep, narrow, and slippery ground, rock slabs with handrails on alpine variants, scree, and in places rappel descents; hands may be needed from stage 1. This is scramble terrain, not glacier or T5/T6 climbing (https://www.pnr.corsica/fr/randonnees-decouverte/gr-20-fra-li-monti, checked 2026-08-24).
How long is GR20?
The OSM 2-D length on this record is 183.6 km (verified). Published figures may differ. See /guides/how-long-is-the-trail
How do I get to GR20?
The record’s base start is Calenzana (OSM line start). A primary gateway on the record is Calvi Sainte-Catherine Airport (CLY). Trailhead transit notes are not included in this public FAQ.
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Featured in
- How long is the trail, really?
- Permit & season calendar
- How hut-to-hut booking works
- Refuge vs ryokan: how hut culture differs
- Difficulty scales and surface
- Seasonality on the catalog
- Water sources on the catalog
- Car-free and transit access
- Government fees and operator markup
- Iconic bucket-list treks
- Hut-to-hut treks in Europe
- Car-free long-distance hikes
- Scrambles & exposed alpine ground
- High-infrastructure treks