GR20 Hiking Guide: All You Need to Know About the Toughest Trek in Europe

GR20 Quick Stats
Distance: 112 miles
Elevation Gain: 43,000 feet
Direction: Most go north to south, though it can be done in either direction
Average Time to Thru-hike: Between 8 and 16 days, depending on your fitness and trip goals
Season: Late May to mid October, depending on snow. Most busy in July and August

Why I hiked the GR20

Growing up with two park ranger parents, I spent a lot of my childhood hiking, paddling, and camping. While I didn’t recognize it at the time, this eventually led me to where I am today. As an outdoor photographer and travel writer, I spend most of my life searching out far-flung trails, routes, and adventures, to then share with others.

I’ve been fortunate to help develop fastpacking routes all over the world, in Japan, Ecuador, Chile, Switzerland, and Greenland. While the GR20 is far from a new route, not many Americans know about it (unlike, for example, the Alta Via 1 in the Dolomites or Stubai High Trail in the Alps), so I decided to see what it was like in person–and the results were surprising.

GR20 Background: What to Know

The Grande Randonnée No. 20, better known as the GR20, is a 112-mile trail that winds through the rugged interior of Corsica, a French island in the Mediterranean. Often referred to as the “toughest trek in Europe,” the trail is rocky and unrelenting, despite being well marked and incredibly scenic. What truly sets the GR20 apart is the solitude you’ll find, especially compared to other classic hikes in Europe.

The origins of the GR20 can be traced back to the 1950s, but it wasn’t until 1972 that the modern route was established. In 2015 a handful of technical sections were closed due to mudslides which tragically killed a group of hikers. Some sections reopened in 2022 as “alternate routes,” although many signs, guidebooks, and trail maps still do not list them, likely to keep inexperienced hikers out of danger. While the revised route is incredibly well-built and well-marked, these alternates are a mixed bag.

As a whole, the GR20 has everything you expect on a classic hut-to-hut hike, from stunning vistas and challenging climbs to rustic refuges. The trail has little to no cell service, no ATMs, and no grocery stores along its entire length, offering a true wilderness experience. Because the mountains are so jagged and formidable, it is easy to forget you’re on a Mediterranean island, until you get glimpses of the ocean.

The GR20 is typically broken into 16 stages with huts at the end of each one, allowing casual hikers to enjoy a leisurely pace by tackling one section per day. Faster hikers may opt for double segments, cutting the time in half. Wanting to move quickly over the terrain, we opted to fastpack the full route and gave ourselves four days to go end to end. And, hoping to see fewer people along the way, we chose to take all of the alternate routes, including the most notorious section, the Cirque of Solitude.

Getting to the GR20

There isn’t an easy way to get to the start or the end of the GR20. The route begins in Calenzana and finishes in Conca (or the opposite, if you hike from south to north) and neither town is large enough to have a train station or buses, so you’ll need to use a mix of transportation to hike the GR20.

The first step is just getting to the island. Corsica has four airports that run daily flights from mainland Europe, not to mention ferries to mainland France and Italy. Coming from the States, we opted to fly to Calvi and take a short cab ride to Calenzana, which in total took a full day of travel from home. Before starting the trail the next morning, we dropped our suitcases off at Cinto Transport, a luggage shuttle service, who transported them to the end of the trail while we were hiking. I’d highly recommend this, regardless of your days on the trail.

Returning to Calvi after the trek isn't straightforward either. There are trains in the north half of the island but not in the south. There are bus lines between the main cities, Porto-Vecchio, Ajaccio, Bastia, and Calvi, but their schedules are hard to find online and subject to change. We found them easier to navigate in person, but still took a full day to get back to Calvi, with windy roads and multiple bus swaps.

Maps & Tips for Navigating the GR20

The GR20 is well marked with red and white blazes painted onto rocks every couple hundred feet. The most challenging navigation is in the alpine, while you are jumping, crawling, and balancing over large boulders. Heavy rain, fog, and other bad weather–which is common in Corsica–will make these sections even harder. Therefore, it’s smart to have offline maps downloaded on your phone before you start hiking (or analog paper maps, if that’s your thing). We ended up not needing our phones often, but in a few crucial spots they came in quite handy, especially on the alternate routes.

Cell Service & Communication

Cell service on the trail is limited, but depending on your provider you can get a bar or two when close to the three small towns you pass. Some of the refuges have Wifi for purchase, but it’s spotty at best. Because of the lack of connectivity, a small satellite communicator, like a Garmin InReach, is a must-have for emergencies. There aren’t many places to bail if something does go wrong, either. The best exit is Vizzavona, the halfway point, which has a train station with direct rides to Ajaccio or Bastia.

Gear We Used for the GR20

We opted to use 18-liter running packs (my go-to is the Patagonia Slope Runner Exploration) and carried just the basics: a change of clothes and lightweight foam birkenstocks for the huts, the lightest puffy jacket available, rain jacket, toiletries, small first aid kit, handheld water filter, headlamp, snacks, and a journal, which I never opened because I was too tired each night.

Thanks to the twenty refuges along the trail, you rarely need to carry more than a day’s worth of food, which helps keep your pack weight lower than most backpacking trips. Also, the huts don’t provide bedding, so most hikers carry sleeping bags. Because we were fastpacking, we decided to sleep in just our puffy jackets, to save weight.

A few pieces of gear really stood out for us: a trusty pair of collapsible running poles, a lightweight pair of sunglasses for the direct alpine sun, and travel protein packs, to help with overnight recovery. Maybe most important was a good pair of well-cushioned trail runners, which could handle both the vert and the technicality. I relied on the Nike Zegama 2.

What to Expect at the Refuges (aka Mountain Huts)

The refuges on the GR20 are cozy, yet very basic. Make sure to carry plenty of cash on your trek, because few of them accept credit cards. Most hut keepers speak the local language, a mix of French and Italian, but some know English, often enough to get by. If not, you can always do a lot with gestures.

All GR20 huts are run by the Parc Naturel Regional de Corse (PNRC) and need to be booked months in advance, because they fill up quickly. For 25 euros you get a twin mattress in a dormitory, potable water, outhouse, and cold shower.

The hut meals are hardy and communal. No prior reservation is required, but make sure you add your name to the list when you arrive, because they do have a max capacity. Beer and wine are available for purchase, which is a nice treat after long days.

Capanelle was the nicest refuge we stayed at, with hot showers, full bar, washing machine, and great food. It gets booked quickly, so you’ll want to plan ahead. All of the refuges along the GR20 have tent spots around them, in case the dorms are full (although some only have a handful, so do your research). Most will offer pre-set up tents with sleeping pads, or you can bring your own camping gear. Wild camping is not permitted on the GR20, but you could probably get away with it in an emergency.

Our Experience Fastpacking the GR20

Like the majority of GR20 hikers, we started in the north and went south, wanting to tackle the harder section first. And sure enough, it started off with a bang. The first nine miles are a steady 6,000-foot climb, which was good foreshadowing for what was to come.

After another two thousand feet of climbing, we diverted from the main route as it descended to Haut Asco. The alternate route stays high on the ridge, a mix of boulder hopping and loose scree. This led us into the Cirque of Solitude, where mudslides killed seven people in 2015. All of the climbing aids in the cirque have been removed, likely to discourage inexperienced hikers. Only go into the cirque if you’re comfortable soloing fourth and low fifth class on granite slabs. If it’s rainy, don’t go.

We finished our first day at Tighiettu Refuge, a modern hut that’s open year-round. The inside has 48 bunks, but is far from the luxuries of the French or Swiss Alps.

The next morning, we climbed up to Bocca di Foggialle and caught the sunrise near the top. The descent to Castel di Vergio was one of our favorite sections of trail, because it was runnable and flowy, a rarity on the GR20. Due to the rocky terrain, even many flat and downhill sections are hard to run. In some sections, it is hard to move faster than a casual walking pace, even with light packs, like ours.

After another big climb and descent, we stopped for an early lunch at Manganu, feasting on a typical Corsican faire of breads, cheese, and charcuterie. Afterwards we climbed up to Bocca alle Porte, to the high point of our route, because we skipped Pointe des Eboulis by going into the Cirque of Solitude.

After a mid-afternoon meal at Petra Piana Refuge, we again left the main route to climb Punta all’ Altore, before reconnecting at Bivouac de l’Onda in the valley. Then came Muratello, the most famous peak on the route, before a long descent to Vizzavona, the midpoint of the trail. Despite 27,000 feet of climbing on our legs already, we continued on to Capannelle for the night, arriving close to sunset.

The next two days flowed much faster, as the trail became less steep and had more runnable sections. After stopping at Col de Verde for lunch on day three, we climbed a couple thousand feet up to Punta della Cappella, which was the beginning of our favorite ridge of the trip. That night we stopped at Usciolu Refuge, a busy yet smaller hut with a sunny deck to relax on.

The last morning started with a seven-mile downhill before a sharp climb up to Bocca Stazzunara, the last notable col of the trip. The final twenty miles are a rolling downhill with a net 5,000-foot loss to Conca, but they aren’t as easy as it sounds. With tired legs, we sauntered through the final section, trying not to explode our quads while soaking up the final miles of the trail.

We arrived in Conca in the late afternoon and were surprised by how quiet it was. Other than Gite de la Tonnelle, where most hikers spend the night, amenities are scarce. In that sense, it would be more fun to finish in Calenzana, which has a collection of restaurants, hotels, and a buzz around the town.