The GR20 is a 15-day, 200km [124 mile] hike across the island of Corsica, France. It has a reputation as a tough hike ("the toughest in Europe" according to some - the Corsican Tourist Board, for one). In June/July, 2010 a mate and I set out to have a crack at it. Here's what we learnt...
The first, and to my mind most important, thing we learnt was that it is a tough hike. In fact I would go so far as to say that toughness is its raison d'être. It is an Endurance Event; a Physical Challenge; the hikers equivalent of a marathon. The French Foreign Legion use it as a training exercise. We hadn't fully appreciated what this all meant beforehand, and really wish we had. It would have significantly changed the way we prepared for this hike, as it is very different from anything either of us had done previously. So why was it so 'tough'? Not for the reasons we had expected: distance; ascent/descent; duration (although these did play their part). The two things that knocked us for six were: the heat; and the conditions underfoot.
The Heat...
Below 1000m [3281'] the typical daytime temperature surpassed my comfort levels for hiking by around 8:30am. I have done a good bit of hiking in Australia, and the heat we experienced in Corsica easily rivalled anything I'd experienced in Oz. The heat also powered some exciting thunderstorm action - around a third of our afternoons were punctuated with a storm. And you seriously don't want to be caught in high places when these storms roll in (I've read that the leading cause of death on this track is lightning strike - not sure if that's true, but it does give one pause for thought). We got caught out twice before we learnt what not to do. The lesson here is: start your day early! Up at 5:00am, and on the track no later than 6:00am is a good rule of thumb. That way you're likely to be above 1000m [3281'] before 8:30am, and at your destination before any thunderstorm rolls in (these mostly hit between 2:00pm and 4:00pm, but can roll in as early as 1:00pm). During our preparations for the hike we had read about this 'early start, early finish' rule, but had dismissed it as the preserve of people desperate to get a place in the refuges before they filled up. We wanted to be much more relaxed about our day. By day three we had learnt our lesson.
The Conditions Underfoot...
... are just awful! Loose rock and stone is all you ever see . Picture walking along a dry river bed, or bottom of a quarry, six to eight hours a day, for 15 days, and you get the idea. In the whole hike we found a single spot that was level and had no rocks - it was about 10m [33'] long, and was worthy of a photograph . It was hard work, and very hard on one's body. It also meant that you had to spend most of the time looking at your feet instead of the scenery. Walking poles were a life-saver in these conditions - literally! I'm not really sure how you would train/prepare for these conditions, either - one misstep and your hike could be over, no matter how fit you are.
So, now that we've returned, what would we do differently next time? How would we prepare?...
When To Go?
'When to go?' is a balancing act between snow, heat and crowds. I would strongly recommend beginning and ending your hike inside one of these two windows: 7th June - 7th July; 7th September - 7th October. Obviously the beginning of the former and the end of the latter has increased risk of snow, and the end of the former and the beginning of the latter has increased risk of heat and crowds. Heat and snow are self explanatory risks. The 'crowds' factor is about pressure on resources at the refuges, particularly food and the pre-erected tents (see 'What To Take' for more about this).
What To Take?
In short, as little a possible - this is not a normal hike, and you should not take what you normally take hiking. If I'd fully and truly appreciated this up front I would not have been forced to ditch quite as much (valuable) gear on the first day as I did. The only things necessary to complete the GR20 are: the clothes you hike in; a water bladder; money; and a sleep system (sleeping bag/mat/liner). Everything else is a luxury and should be treated as such (i.e. not necessarily left at home, but only brought along for very good reasons). Let me explain...
Shelter: as hard as it may be to do, don't bring a tent. All the refuges have plenty of pre-erected tents, with plenty of spares should these fill up. These two-person tents can be pre-booked, and cost the same as a bare tent site for two people. If you walk during the recommended time slots, you will not miss out on these. You may want to bring a super-light-weight bivvy sack to round out your sleep system (if you're the cautious type). Seriously, don't bring a tent.
Sleep system: a summer-weight sleeping bag is sufficient. I had a 13°C (comfort)/10°C (limit) bag plus liner, which was just about OK. I'd go a 10°C (comfort) bag next time. The pre-erected tents mostly came with a foam mat, but they looked a bit skanky to me...
Food/Drink: don't bring in any food, nor any cooking/eating gear. We only had difficulty getting a cooked meal at one refuge on the whole track, and DIY food supplies were readily available everywhere. I can recommend skipping the refuge breakfast, and always having a full day's supply of food in your pack (in case the dinner and/or supply situation has an unexpected outage one day). The cooked meal each night cost between €9 and €20 and was always substantial (we never experienced the kind of mean portions that people have talked about in the past). The only eating gear worth bringing is a light-weight plastic cup and spoon/spork, plus a small knife for hacking up cheese/salami/etc. I left the Swiss Army Knife at home and didn't miss it (it's shite for cutting up food, anyway - too hard to keep clean). With regards to your water bladder, a 3-litre capacity is useful sometimes, but you'll only need 2-litres most of the time. If you walk during the recommended time slots, you will find at least one water source midway along each track stage (i.e. in addition to the start and finish).
Clothing: two sets - one to walk in, and one to lounge/sleep in. Both sets should be light-weight, quick-drying and include full-length arm/leg cover. I don't usually hike in trousers, but I would on this track - the sun is fierce, as is the marquis (thorny undergrowth that grows about calf-height). Shade at the refuges is non-existent, and my only post-hike cover was my far-too-warm fleece. Washing and fully drying your walking clothes each afternoon is always doable (sun/heat/wind are never in short supply). A wide-brimmed hat, a medium-grade fleece, and an ultra-light-weight raincoat are the only other clothes you might require (I only used my raincoat once).
Boots: these take quite a hammering on this track, so bring a pair you're very happy with. They need to provide good underfoot protection/support, but also have the kind of sole that can friction-grip on a 60° slab of granite.
Route-finding: track markings were excellent and extremely regular. Leave the maps at home. A GPS and/or guidebook is a luxury, but could be useful if you get into trouble and/or want to make a non-standard entry to/exit from the track. Do keep your eyes open for the track markings - if you've not seen one for more than 50m [164'] then you've probably gone wrong. This usually occurs at a switch back or where the track switches to the other side of a ridge. It's remarkable how quickly a track-like path emerges once a few people make the same mistake...
Torch: don't need to bring one as you'll be getting up with the sun and in bed before it sets.
Sundry: toilet paper; toothbrush+toothpaste; small towel/flannel.
Everything else is a luxury. Keep that pack weight under 10kg, including water, if at all possible - your knees and feet will thank you for it. I repeat: this is not a normal hike, and you should not take what you normally take hiking!
