GR 20

The GR 20 is one of the extensive Grande Randonnée (or GR) network of paths and trails. The trail traverses Corsica's mountains, with its end points in Calenzana in the north and Conca in the south, running most of the length of the island. It is often referred to as "the toughest long distance trail in Europe", covering a distance of 180 km and around 12,000 to 13,000 metres of climbing and descent, over rugged terrain.

Route
The trail is normally done in 16 days if you stay at all the refuges, however, people often do it in less. Some of the stages are very short and can be combined. So don't just naively book all the refuges, do some planning about which stages to combine and which refuges to skip. In addition, you don't always have to stay in refuges: there are some private bergeries and hotels. Sometimes staying in a bergerie or hotel makes more sense if it breaks the route into more manageable stages. Also check transport timetables before making any bookings: buses don't run every day.

The route may be walked in either direction. Most people start in the north, however starting in the south creates a nice build up in required effort. Many people walk just half the route, and come back the following year to do the other half. Vizzavona is an ideal place to start or stop, because it has a train station. If you only have time to do half the route, the northern half has the rugged highlights including Monte Cinto, but is slightly longer.

The route is very regularly marked with the white and red stripes of the GR symbol. The route is so well marked that if you lose sight of the markers, you must retrace your steps immediately until you find the route again. It is completely possible to do the whole route without a map, but take one, anyway, as a safety backup.

The route is absolutely unsuitable for children and young teenagers. Some groups of older teenagers do it. It is suitable for adults of all ages, as long as they can manage climbs over boulders and fairly steep rock faces.

The trail passes close to the summits of several mountains, so you can relatively easily make detours to these summits.

The route mostly stays away from civilisation, but occasionally passes through small towns. There is also the possibility at some points to make detours to local villages.

The season

 * The season runs from 22 May to 2 October. You can't book the refuges out of season. Refuges will be open but unstaffed, with no food or fuel. The water may be turned off.
 * Snow will still be present in late May, but will mostly be clear by June, so you don't need specialist equipment such as axes or crampons in season.
 * July and August are the hottest months, and there is a risk of thunderstorms. Some water supplies may dry up.
 * Early September is a good time to go, you will avoid the worst of the sun but it will still be fairly warm with little rain. Buses don't run every day, so check the timetables. Taxi rides can be expensive.
 * From October, refuges are again unstaffed, without food or fuel. Snowfall is likely and will obscure the route.

Getting in and out
Bastia Airport typically has the cheapest flights.

From Bastia Airport to Bastia train station, you can take a bus for €10 as of 2023, but check the timetable to make sure it is running that day. Bastia Airport bus timetable You can also take a taxi, but if the traffic is bad it can cost over €60 (as of 2022).

Calenzana
You can get a bus between Calvi and Calenza for €8 as of 2021. Timetables are here. From 1 July to 4 September, there are two buses each day in both directions. From 5 September, buses from Calvi to Calenzana only run on Monday, Tuesday, Thursday and Friday at 15:30, and there are no buses from Calenzana to Calvi. You could walk it in 3 hours, take a taxi, or even hitchhike.

You can take a train between Bastia and Calvi for €16.40 as of 2022. Train schedules are here. A taxi from Calvi airport costs approximately €30 as of 2022.

Vizzavona
You can take a train to Vizzavona from Calvi, Bastia or Ajaccio. Ajaccio is quickest, you can go straight from the airport.

The train between Vizzavona and Bastia town costs €14.60 as of 2022. Train schedules are here.

Conca
You can get a bus between Bastia and Ste Lucie de Porto-Vecchio (6km from Conca). It does not run every day, see here for details. See Rapides Bleus to view the schedule and book tickets. Price is €30 per person and €1 per bag as of 2024. In July and August only, the northbound bus can drop off passengers directly at Bastia Airport. The bus stop in Ste Lucie de Porto-Vecchio is opposite the Bar U Colombu.

To get from Conca to Ste Lucie de Porto-Vecchio, Gîte étape la Tonnelle used to run a shuttle bus, however as of 2024 it is suspended until further notice. You may be able to get an Uber instead, or the hike is 1 hour 15 minutes.

Maps

 * Corsica High Route GR20 IGN 89027. One map covering the whole route, plastified for waterproofing. Scale 1:50000.
 * Carte de Randonnée 4149 OT - 4253 OT and 4253 ET (6 maps). Scale 1:25000. Much more expensive because you have to buy six maps.
 * Le GR 20 Corse (Fra li monti). Editions Didier Richard. ISBN 9782344000434. Scale 1:50000.

Sleeping
You must bring your own sleeping bag.

The "official" refuges can be booked through the National Parc website. It is cheaper to book in advance, and guarantees you a place. For example, a dorm bed (bât flanc) is €17 in advance or €22 on the day as of 2024. Booking opens at the beginning of February. Official refuges can be booked for 22 May until 2 October. A few additional private refuges ("bergeries", literally "sheepfolds") and hotels exist on the route. Bergerie accommodation is similarly priced to the national park refuges. Hotels are present at a couple of places along the trail but are much more expensive.

Most refuges have a dormitory, as well as tents with air mattresses for rent, and space for your own tent. Some refuges do not have dormitories. If you cannot book a dorm bed, try booking a tent ("bivouac") for that refuge instead. Tents are a bit more private. There is little reason to bring your own tent or roll mat, it is just extra weight to carry and time to set it up. Wild camping is not allowed, you must pay to stay at the refuges even if you bring your own tent.

Most refuges do not accept payment cards, so you must bring cash. As a general rule, if a refuge doesn't have phone signal, it will not accept payment cards.

Refuges typically have hot showers, space to cook, a drinkable water supply, and a small shop selling food and alcohol. They will sell you dinner, breakfast and a packed lunch if you want. Dinner must typically be booked by 17:00 (sometimes 16:30). Breakfast and packed lunch must be booked the night before.

Most refuges have plug sockets to charge your phone, but some charge for this service. At refuges where it's free, the plug sockets are typically in high demand!

Most refuges don't have phone signal, but you will typically find phone signal during the day at some point along each stage.

Food
Refuges will sell you dinner, breakfast and a packed lunch. Dinner must be booked by 17:00 (sometimes 16:30). Typical prices as of 2022 are at least €20 for dinner, and approximately €10 for breakfast and €10 for a packed lunch. Wine and beer are also available (try the chestnut beer, typically €8 for 50cl).

Refuges also have a small shop selling things such as cheese, saucisson, and snack-bars.

In the south of the island below Vizzavona you can often get fresh bread, however you can often get "long life" bread otherwise.

Meals at refuges are typically high carb, low protein, low vegetables. You may wish to take some protein bars with you.

Dinner is typically a three course meal with lots of pasta for the main course. There might be some tomatoes, tuna, cheese, or chocolate mousse. Food is expensive for what it is, you're not paying for quality, you're paying for the food to be delivered up a mountain. That said, the guardians often put in a decent effort.

Breakfast is typically old bread, butter and jam, fruit juice and a hot drink. It's very expensive for what it is - if you're trying to save money, this is the meal to skip. Have an energy bar instead. You can stock up on calories in the evening. If you do decide to have breakfast, you can stock up on calories by eating lots of bread.

You'll probably find that buying 3 meals per day at the refuges is too much food.

At the towns such as Asco and Vizzavona, there are restaurants, and greater variety in the shops.

Water
There are usually marked water sources near all of the refuges, though some years a refuge will lack water. There are also the occasional marked sources on route which are safe to drink. Springs dry up in the summer months and there are some long ridges without points of resupply. You should carry at least 2 L of water, and drink a litre of water before you leave each refuge.

Fuel and cooking
If you want to save money or have a special diet, taking your own food will add weight, so try to take light-weight, energy-dense food.

Most refuges have areas with stoves and pans. These can get busy, or sometimes don't work, so if you want to cook your own food it may be a good idea to take a stove along. If you don't mind cold meals, not taking a stove will save weight.
 * Meths is fairly easy to find in supermarkets, it's sold as cooking alcohol, and won't block Trangias up.
 * Screw-top gas canisters are difficult to find however were available in Calvi in 2008.
 * Press-top gas is fairly easy to find.

Gear
Take as little as possible, pack light! Keep the weight of your rucksack below 15 kg (ideally below 10 kg), including 2 L of water.

Required

 * Rucksack with waterproof cover. 40-50 L is about right.
 * Water bottles. 2 L total
 * Rugged boots - you can easily wear out a set of lightweight walking shoes on the trail. Some people choose to wear lightweight walking shoes to save weight, treating them as disposable.
 * High-visibility quick-dry clothing. Approximately 4-5 sets so you can wash and dry some sets while using the others.
 * Sun protection cream (high factor).
 * Ultra-lightweight wind & waterproof.
 * Fleece top. It can get cold!
 * Quick dry towel
 * Sleeping bag
 * Toothbrush, wash-kit, etc.
 * First aid kit, including plasters to cover/prevent blisters
 * Toilet paper. You can buy tissues from the refuge shops, but free toilet paper is not provided.
 * Cash

Recommended

 * A map. It is entirely possible to do the GR20 without a map, however it would be wise to bring one and a compass. Alternatively, a smartphone with an app like Google Maps and the Corsica maps downloaded will provide your GPS location. More advanced users can download hiking apps with the exact route.
 * Head torch
 * Plastic bags
 * Energy bars
 * Protein bars
 * Mobile phone for safety. Phone charger, European plug adapter, external battery back. Camera.
 * Survival bag
 * Insurance

Optional

 * Brimmed hat, long-sleeved shirt and trousers, sunglasses.
 * Tent that will stand without need for pegs, and air mattress (the ground is usually very rocky). If you hire a tent, it will cost more but save weight and time.
 * Walking poles. About 50% of walkers use these, but they can get in the way when clambering over boulders or holding on to chains.
 * Detergent for clothes (or just a bar of soap)
 * Moisturiser, shampoo, body wash
 * Food, stove

General advice

 * Walk early for safety. You will avoid the worst of the sun, other people will find you if you get into difficulty, and you will have more contingency time if things go wrong. In the dormitories, most people set their alarms for 06:00 so you will probably be woken up then! Aim to depart by 07:00 each day.
 * Only few refuges give written weather reports, ask the guardian for info.
 * Bring cash along. Most refuges are cash only. You should book refuges in advance to reduce the amount of cash you have to carry (and to save money), however this reduces your flexibility. As of 2022, approximately €40 a day will cover 3 meals. You can save money by bringing your own food, but this adds considerable weight. You can also save money by eating lots at breakfast and dinner and skipping lunch. If you want to drink alcohol, bring extra money to cover it.

Books

 * Dillon, Paddy: "The GR20 Corsica: The High Level Route" (Fourth edition, 2016). Cicerone. ISBN 9781852848521