Field notes
Mistakes to avoid on the GR20
The GR20 doesn't only punish the poorly prepared. It also punishes plans that are too rigid, packs that are too heavy, starts that are too fast and the small bits of carelessness you then drag along for twelve days.
The classics
10 mistakes that cost you dearly
1. Setting off too heavy
A pointless kilo doesn't stay just a kilo. It becomes a drag on the climbs, a strain on the shoulders, then a real burden on the descents.
2. Burning out at the start
The first day makes you want to prove something. Bad idea. The GR20 is more often won through restraint than through pride.
3. Underestimating the descents
The climbs are impressive, but the descents are what wreck you. Knees, ankles, focus: that's often where the fatigue starts to show.
4. Mismanaging your water
It's not enough to know there'll be a spring. You need to know where, how far off, and what to do if it's barely flowing or you get there too late.
5. Ignoring the weather
A storm in the Corsican mountains is no minor inconvenience. It can turn a slab, a ridge or a scree field into a very bad place to be.
6. Trusting the GPX too much
A track helps, but it's no substitute for the waymarking, the guidebook, clear thinking and the ability to back off if the terrain no longer matches the plan.
7. Booking with no margin
An itinerary locked down to the letter feels reassuring. In reality it can turn fragile the moment a niggle, a poor night's sleep or a storm throws the day off.
8. Setting off too late
In summer, the heat and afternoon storms punish late starts. Experienced hikers leave early, clear the exposed sections in the morning and arrive before the weather turns.
9. Neglecting your feet
Blisters are one of the leading avoidable causes of giving up. You treat every hot spot the moment you feel it, you don't walk in unbroken-in boots, and you keep your feet dry.
10. Underestimating how long it takes
The Park's official times climb to 7 or 8 hours on the big stages, not counting breaks. Add in photos, meals and fatigue, and a day soon overruns. Set off with a margin, not cutting it fine.
Gear
Pack weight matters more than you think
The trap is packing your bag to reassure yourself, not to walk. On the GR20, every item has to have a clear purpose. Duplicates, "just in case" clothing, comfort extras and badly judged reserves all end up speaking up in your thighs.
Pace
The right tempo isn't always fast
What helped us: setting off humble, drinking before the hard part hits, eating regularly, accepting the breaks that count and not turning every day into a test of ego.
Safety
Weather, snow and terrain: check right to the end
The GR20 crosses high-altitude terrain. Early in the season, snow can make some stages serious; in summer, the heat and the storms force early starts; late in the season, the days shorten and services thin out.
The right reflex: check the PNRC's information, look at Météo-France, ask the wardens, and keep a mental margin to adapt the plan.
Water
The stages where water really runs short
On the GR20, some sections offer no reliable water point for hours. The Park flags this itself on several stages: it's safety information, not a comfort detail.
Ortu di u Piobbu → Carrozzu
The Park warns that you won't find another drop of water until Carrozzu once you've passed the spring at the start. You fill your bottles before leaving the refuge.
Carrozzu → Ascu Stagnu
A stage known to be without water along its whole length. Watch out: the water from the Muvrella lake is flagged as unfit to drink. You set off with a proper reserve.
Prati → Usciolu
A mostly open ridge section, with a water shortage flagged in July and August. The heat and exposure make the need worse still.
The reflex: top up at every safe water point and never leave a refuge dry, gambling on a spring further along. On the flagged stages, your reserve is sorted at the start, not on the way.
Navigation
The GPX is a tool, not a permit
A downloaded track won't tell you whether a passage is slippery, whether a snowfield is hard, whether a footbridge is closed, or whether you're still clear-headed enough to carry on. It helps you read the route, but the decision stays on the ground.
A concrete example: the Cirque de la Solitude, long the stuff of legend, has been closed and stripped of its fixed gear since the deadly rockfalls of 2015. The diversion has become the official route. An old GPX track can still send you that way: all the more reason to follow the waymarking and the up-to-date official information.
Sources
To check before you go
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