There are 4 ways of doing the GR20. Regardless which you chose, you always should go the lightest possible. I also do not find it interesting to do the GR20 South to North, so I discuss only the North to South direction traverse. In addition, when you finished in Conca, the best beaches of the island will be offered around Porto Vecchio.

The magnificent 4: 

  • Self sufficient with your own tent
  • Sleeping in a hired tent
  • Sleeping in a refuge / mountain hut / shepherds hut (bergerie)
  • Doing it non-stop (supported / unsupported)

Camping, bivouacking or sleeping anywhere else outside of the refuge is illegal. The island of Corsica lives from its tourisme and they need all resources. The PNRC , guardians / hut-keepers and the firemen work very hard to keep the GR20 clean. I would not recommend to try wild-camping to obey the rule of: ” – Never f..k with a Corsican ! ” These are very proud and independent people. Work by their rules and all good to go. Behave like an outsider and you are in trouble !

Best Period for Completing the GR20

Depending on the harshness of the previous winter, the best period is end of June and beginning of July. Of course if the snow is melted from the high mountain passes before this, you can go ahead and do it in May, but it is rarely the case, maybe once in 20 years. So let’s stick to the end of June and beginning of July.

If you knew basic navigation, you were amateur, but sure crampon and ice axe user, from April you can go ahead. In this case, I would highly recommend to access the trail at least by a party of two !

The weather starts stabilising in July through August. Beforehand you might experience some light afternoon storms with sever temperature drops. From 26°C to 6°C in 20 minutes at 2000m altitude. These storms come back at the end of August with much lighter temperature drops, but with brutal light and thunder. The weather stabilises again around mid-September till mid-November. Kind Of !

Water access is also something to be concerned about. From December to the beginning of July, depending on a lot of things of course, 1 to 1,5L of water would be enough as there are springs all over the GR20. However a lot of them completely dries out from July to October.
When heat starts creeping in,  2,5 to 3L of water-bladder and a lot of bathing is necessary if you wanted to advance with a descent speed. Last year I filled up my bladder maybe twice a day consuming 3 to 3,5L, while this July I was around 6 to 8L a day.

Most mountain huts are open from the 15 of June to the 15th of September. This means that if you wanted to go light and use the refuges as aid-stations in trail running mode, this should be your chosen timeframe.

Late summer forest-fires are always a big concern. Avoid, the crowded months of end of July / August and beginning of September. I had to cut short this year’s GR20 as running between flames was not pleasant. There was also a lot of smoke even in the fire-free areas and muscle and brain oxygenation became a serious problem.

For all information on weather, fires, water, accessibility, check the following websites regularly and contact them if needed

  • http://randoblogpnrc.blogspot.fr/
  • adminblogpnrc@gmail.com – send an email for trail-info, on French if possible: snow conditions, trail closure, forest-fire
  • http://www.le-gr20.fr/
  • You can book your stay in a refuge or hire a tent here: http://www.pnr.corsica/
  • If you went in the beginning of the no-snow period, reservation is not necessary at all and you’ll find free tents and places inside the refuge too. In 2017 tent places were 7 Euro. Hired tents were 7euro + 11euro per person( 18for 1p and 25for 2p). In -refuge stay would be 12 to 20euros , depending on many things.
  • Warning !!! Despite the cleanliness of refuges the high visit rates are creating bed-bug infestations. Some refuges are often closed down, most likely in July August. I would not recommend sleeping in a hut, outside of the January to June period.

Length in time : 3 days / 1 week / 2 weeks ?

It depends on hiking and mountaineering experience and determination. There are 15 stages and 95% of people choose to do them in 10 to 14 days. This is not going to be your average walking trip, nor your regular trail running excursion. As a walker, you must learn some basic scrambling, must learn how to use poles and definitely strengthen your ankles. As a trail runner, the steepness of the trails and the harshness of the terrain necessitates a lot of muscular resistance. Instead of your regular preparation of going out doing long outings all the time, I would hit the gym to lift heavy and would do intervals. Balance board work with weights, slack-lining and a strong core would be definitely an advantage.

The record is 31 hours 06 minutes. If you were able to move fast on very harsh terrain, it is definitely doable in 2 days of moving 2 x 18 hours for instance or 3 days of 3 x 15hours. Breaking it down is not easy, if you’ve never done it before. You cannot just split it up for 2 x 90kms or 3 x 60km. By visiting Monte Cinto, the highest point on the Island, the first 40km offers you the gift of over D+4500m of elevation gain and around D-4000m of loss. This is nearly half of the total GR’s altitude gain on 1/5th of the total distance.

Here are some tips of doing it on certain intervals. The distances and elevation gain are approximate, but can give you a rough idea about the proportions:

3 days

7 days

  • Calenzana – Piobbu
    • 12km D+1500m
    • Easy warming up day to start at the afternoon. Lot of people already crack here, this is why, it is great to get into the groove by hitting the trail with this easy section.
  • Piobbu – Asco
    • 18km D+2500m
    • Very rocky technical terrain, with some chained-up sections. Take your time. When arrive to the plateau after the big climb from Carozzu, there is small lake welcoming you to chill. A last climb, some scrambling and brutal descent will follow, before the arrival to Asco. Food and cold drinks available.
  • Asco – Refuge Mori
    • 25km D+2000m
    • First real difficulty with 2 steep climbs. To go up to Monte Cinto first. This can be technical and dangerous if you went when snow was present. Crampons would be necessary. The descent to Tigjettu would also challenge your resistance, before you hit another 1000m climb to Refuge Mori. Take a lot of water with you and don’t hesitate to grab on the multiple occasions of bathing !!!
  • Refuge Mori – Petra Piana
    • 25km D+1500m
    • Water is again a great importance. After a big descent and 2 important refuel points at Col de Vergio and Refuge Manganu, you’ll tackle a big technical section. Often hikers run out of liquids around Lac Nino, but the spring is usually dried out !!! Take water.
    • If you moved fast with a back pack under 10kilos, your latest start from Manganu should not be after 16:00. If your rucksack weighed over 10kg, do not start after 14:00 !!! I mean, I am not afraid of night navigation, in rain and fog with 5 to 10meters of visibility on hostile terrain when exhausted, are you ?
  • Petra Piana – Capanelle
    • 25km D+2000m
    • While descending from the refuge, you pass by the Bergerie de Tolla on your right. This is the one to visit for Saussages, Copa, l’Onzo and cheese !!! You’ll hit 1 big climb with a slippery technical descent. Move slowly at the beginning and mind your steps all the way to Vizzavone. Swim in the creeks ! Fuel up a little and keep on climbing to Capanelle, where you can buy food for your next day, but also enjoy a restaurant with very good food !!!
  • Capannelle – Bergerie de Croce 
    • 35km D+1800m
    • A lot of little climbs and cow encounters.
  • Bergerie de CroceConca
    • 40km D+2000m
    • Final descent, with some scrambling.

Variaties (Variantes)

If you were not happy about the difficulty of the GR20, you can add some, by tackling the Variante Alpins ! These are basically the old routes, what were made easier for the grand public. You must be in brutally good shape, if you wanted to add all of them in one single go. They will double up the difficulty of the GR20, by adding around 3 to 4000m of elevation gain to it with significant amount of scrambling.

  1. Climbing Monte Cinto. This will add a couple of hundred meters of elevation gain and takes about 1 hour of an out and back route. Easy to find following the red spots from the col the Monte Cinto in the opposite direction of the GR.

Variante Alpin 00005

2. From Petra Piana you can take the variante to Refuge de l’Onda on the double yellow sign. Light scrambling and slow terrain will challenge your willpower.

Variante Alpin 00006

3. Climbing up from l’Onda, when you pass through the col and start descending, you can again see the double yellow sign, staying on the crest.  This is the Variante Monte d’Oro to arrive to Vizzavone. Another nice scrambling variation.

Variante Alpin 00007

4. From Col de Vizzavone the non-official variante of Punta Dell’Oriente will bring you to Ref. Capanelle.

Variante Alpin 00001

5. From Capanelle you climb by Lac Bastani and the Monte Renoso to arrive to Col de Verde.

Variante Alpin 00002

6. From Ref. Usciolu you can go left leaving the GR to arrive to Asinau. In fact the GR20 will follow a line of Shepperd Huts (business line) to offer you a good night sleep, but the scenic way will be on the left.

Variante Alpin 00003

7. Your last and most scenic variante will be the Les Aiguilles de Bavella, just after the descent from Asinau. This will enhance your skills with some chain and ladder use.

Variante Alpin 00004

Doing al the variantes in one go will result in a little bit shorter overall distance, but with added 3 to 4000m of elevation gain, if not more. This will be my plan for next year, to do all the variantes in one go and stick to a 3 days schedule in the meantime.

Physical Training for the GR20

This is the most important part. To understand your current fitness level and to compare it to the one you would need for the planned timeframe of traverse ! If you can do D+3000m of elevation gain on any given Sunday and life goes on without any soreness or pain, you are good to go for a shorter schedule of 3 to 5 days. Of course it depends on weather, backpack weight and other factors too, but now we talk about fitness. If moving more than 10hours at one go or doing back to back 10h+ days on harsh terrain with a heavy pack sounds like pain in the ass, well, you’ll probably need some extra training or maybe you must completely reschedule your trip. There are around 50% of all hikers abandon the trail each year, just because of lack of fitness.

What would I recommend as physical training ? It depends on your goal. If you wanted to complete it in 3 days with no carried tent, just the necessary clothing, some food and a sleeping bag liner, you must trail run. Fastpacking / trail running on very technical terrain with a lot of elevation gain and doing back to back days of this type of training will be the most enjoyable process with a lot of benefits. Your bag must be under 6kg !

You wanted to do the same in complete self sufficiency ? Moving fast with a slightly heavier 7 to 10kg backpack ? Completing it in 3 to 7days ? You would need a bit more resistance and I would definitely recommend some extra strength and conditioning and core training. We talk about regular bodyweight drills. Squat jumps, lunges pushups, pull-ups, sledge pulling, farmer’s walk.
Trail running with a lighter trail-vest is a good idea to construct endurance, but getting in a longer outing every 10th day with your exact planned gear is a must ! I saw many scrawny runners suffering under the light load of 8kg while some beefy hikers carry up to 20kg big back packs !!!

If you liked to suffer and listened to te advice of outdoor-shop-salesmen, you’ll carry a 12 to 25kg backpack. This is going to hurt ! During my very first traverse, we carried this weight with my wife, because huts were not yet open and snow/ice was still present, so carrying an ice-axe, mountaineering boots and crampons were completely unavoidable.
In this case, get an at least 3month gym membership and start working with heavy weights. This will be your best bet against back pain, twisted ankles, dislocated hips and patellar pain !
Training too regularly with a pack of this weight and size, is not fun, nor would it be too advisable. Get a lighter pack to train regularly, max 10kg and use the GR20pack occasionally for shorter outings. I love doing “hunter intervals” with a loaded pack  for instance:

  • Take a 20 to 30kg backpack
  • 25min easy warm up walk
  • Take off your back pack on the left, put it back on the left. Readjust.
  • Take off your back pack on the right, put it back on the right. Readjust.
  • 10 proper squats (Using hiking poles)
  • 1min very-hard uphill walk
  • 5pushups
  • Take off your pack on any side.
  • 10 pushups
  • 2min rest

You can decrease the number of exercises and intensity or increase them. You can add overhead presses with your pack, lunges by using your hiking poles, building a windshield from heavy stones, pulling yourself up on a near vertical slope on a climbing rope and so. These kind of training sessions will drastically augment your overall fitness in addition to the bodily resistance gained from handling the heavy pack. Takes no time ! In 45 to 50minutes you gain as much as from a hike of 5hours !
This does not mean, that you can neglect the occasional 10h+ outings, but that, once every 2 to 3weeks can be more than enough, if you maintained your regular training schedule.

I think you understand the concept. The faster you wanted to complete, the more aerobic training you would need. The heavier the pack you carried, the more strength and conditioning would benefit you.

My personal opinion: On the GR20, there is no point to carry more than 13kg, even in case of complete self sufficiency ! You’ll see in the gear section, that if you started with an empty backpack of 1.5kg or more, you are already on the wrong path !!!

Gear for the GR20

This is the most important part of your trip after your fitness, if not equally important. Having the most efficient gear for your needs and knowing how to use it and pack it, will save you enormous amount of time, effort and pain !

Shoes, socks and Backpack – 3 Keys to success

You must choose these three together. The heavier you go, the more support you need. Trail running shoes are comfortable up to 6kg pack size, light walking shoes would serve you up to 10kg weight and heavy duty, but still relatively light shoes would be great if you went over 10kg. Choosing a boot, is an option, but I would rather recommend strength training and ankle stability drills, than casting your feet and ankles. There is always one thing to remember: if you twisted an ankle, broke it or snapped something inside, there are so many tendons, muscles and ligaments what can replace each other’s functions ! However when your ankle is completely locked in a boot, the first thing what will give, are your knees and the second are your hips. However this will be for life ! Better to strengthen those ankles and to wear shoes, not extremely hot, stiff and non-flexible hiking boots ! Yeah, sure, walking is a skill, like running and swimming and 90% of all people must relearn how to walk. My walking and running shoes last over 1000kms always and much more. If you were somebody using up hiking equipment much faster, you must expand your knowledge about technique of moving on harsh terrain !!!

Trail running style 6-7kg:

  • Altra Lone Peak + Injinji Trail socks + OMM Phantom 20
  • Salomon Sense Ultra + X-Socks Trail Perf + Salomon Peak / S-Lab Peak 20L
  • Inov 8 Roclite 290 + All Terrain Sock Inov 8 + Inov 8 All Terrain 25L pack

Speed Hiking Style 8-10kg:

  • La Sportiva TX3 + X-Socks Trek Superlight + OMM Classic 32
  • Adidas Terrex Agravic + Drymax Lite Hiking Crew Socks + UD FastPack 35
  • Merrell All Out Blaze 2 + Smartwool Light Hiking Socks + Salomon Peak 30L

Light Hiking Style 10-15kg:

  • La Sportiva TX4 + X-Socks Trek Light + Osprey Exos 48 or 58 Pack
  • Merrell Chameleon + Icebreaker Hike Lite + HMG 3400 SouthWest Pack
  • Garmont Dragontail + Rywan socks + ZPacks Arc Blast 55 Pack

This is just a guide, but you can go always lighter or heavier. It also depends on your budget, as for instance if I could invest thousands of dollars into gear, I could go in complete self sufficiency under 7kg !!!

Tent

I recommend something light and very easy to set up. Waterproofness is not an issue, of course depending on the period of the year. I prefer self-supporting / free-standing tents. First year we went heavy with my wife and needed some comfort too, so the MSR Elixir was our choice. You can go much lighter by choosing the HuBBa NX 2 or a Carbon Reflex.

Don’t forget, on the GR20, you can camp only near the huts ! Bivouacking is totally illegal and if a shepherd, camp owner or a park ranger catches you, they gonna fine you and harass you off the GR20. They demand huge respect for their island.

IF you planned going ultra light, a Carbon reflex, or a Camp Minima would serve you well. I chose a Ferrino Bivy Tent, what is only for sleeping. If you were sure that the weather is okay for the night, you definitely can sleep under the sky. Setting up a tarp is also doable, but in certain situations, ground humidity can be a great issue.

Advice: Add 30 to 45cm extra cord loops to your peg-points. There are many camping grounds, where using pegs is completely impossible due to the hard ground conditions. You can still fix and tighten your tent by using big heavy stones. In most camps this will be the case.
You can also hire a tent, and it is more advisable to do so, than sleeping in the very often bedbug infested refuges. Hiring a tent would cost 7 + 12 euros a night or 7 + 7 + 12 for two persons. Tent places are 7euro. 

Clothing

  • 1 short
  • 2 underwear (what you can wash after each day )
  • 2 t-shirts (what you can wash after each day )
  • 1 x-bionic 3/4
  • 1 pair of X-Bionic Arm-Warmers
  • 1 Uberlight downjacket like MH Gostwhisperer
  • 1 Event / GoreTex Jacket like a Montane or a Gore Running
  • 2 Buffs and 1 cycling cap
  • I don’t often use sunglasses, but can be a good idea to have a bigger “cycling mask” like an M-Frame, Radar, Julbo Trek or something on this line, to protect your face against sunburn !
20597442_10212914190825155_2836632576979977680_n
100% self supported. Just under 10kg with 2L of water included !

Even if you went in June, outside of 1 or 2 chilly nights, you’ll be hot. If you went heavier, you can add a longer trouser, a micro fleece and a waterproof over-trouser.

Nutrition, Cooking and hydration 

If you went in-season (15 June – 15 September) , you can use the cooking facilities of all refuges. This is part of the fee, that you pay for your campsite. There is gas, stove tops and pans, saucepans, frying pans. Spring and autumn time, there is risk of not having these comforts installed.

If you went light, I would recommend a low glycemic index meal replacement powder to be used during your long days, in addition to a light breakfast, a medium lunch and a heavy dinner. I used Ambronite the first year and Nano the second one. Both worked great, however Nano – even if it is less healthier than Ambronite – has 600kcals par sachet instead of only 400 and digests faster !

For breakfast, lunch and dinner I ate local sausages, cheese with a slice of bread ! I adapt to what I can buy. On the GR20 you cannot get a moringa-spinach-almondmilk-banana smoothie with spiruline tabs and coconut cream topping ! This why, even if I am not a big fan of it, I eat some gluten, some diary and some crap during my every day life. If you haven’t eaten pasta, lentils and goat-cheese for 5years and this was the only thing you could get during a hike, you would be in big trouble digesting it. I adapt to what I want to do.
The same true to calories. Most people have stomach upset, nausea or constipation, because of un-adapted stomach. If your life demands 2500kcals a day for a decade and suddenly you try to shove down on the “tube” the double of it, you’re stomach will say: Hell No ! Same true to oils and fats. I can do olive oil shots and butter slices if needed during long and slow events, but it needs practice !

TIPS:

  • Have enough cash for the whole journey as ATMs are non-existent. There might be 3 / 4 places where you can pay with a normal credit card on the whole trip and when a storm is in, it won’t work either ! No American Express at all, only MC or Visa ! So have cash !
  • Have at least 5 patches of compeed with you
  • Bring a digestive aid like citrate de betaine (Betain HCL) and a detoxifying agent like activated charcoal powder ! You don’t want to abandon or get messed up on the trail because of a small infection. 9 out of 10 hikers experience stomach issues during the GR20 !
  • If you were really sensitive, use a Katadyn or Water2GO purification bottle all the time !
  • Book your trip properly as local transport is crazy unorganised and self driven. Have at least 2 days to spare !!! That means that if the bus driver decides to arrive late and during the trip he wants to pick up his friends or stop chatting and smoke a cigarette, he will do that. Also the ferry is late 9 out of 10 times.
  • Taxi is expensive and unreliable. They are not too frequent either, so you must have a phone number as you cannot just hitch a ride from the roadside! Sunday fares are even more expensive !
  • Hitchhiking works ! From the middle of nowhere, I found 6cars in 5hours to get to Ajaccio !
  • Do not eat much in the refuges, but favour the shepherd-huts ! L’onzo, copa, sausages, goat and sheep cheese and of course the local bakery produce !
  • Do not miss the opportunities to have a bath in the creeks. It will cool you down, work as a shower and rejuvenate your whole body !
  • Learn how to enjoy life and basic foods. It is faster, cheaper and more efficient, than eating and waiting in a restaurant. For instance in Vizzavone, I found eggs, tartare and some veggies. An immediate beefy omelette I made in just 20minutes and had 6boiled eggs next morning.
  • Learn how to control your effort and learn about endurance. The body likes to slowly warm up and to move with a regular effort all day ! 90% of all hikers and trail runners start each day too fast, get into the red zone on each climb and feel like smoked every night. As a 35 year old your HR should never go over 145 ! There is no point, even if you went for a serious time !
  • Last but not least, enjoy every single moment of the trip ! If you were out of your comfort zone, you might be doing something really not right !

This article might not cover everything. If you had questions, suggestions or other info to add, please leave a comment !!!