Practical advice
Preparing for the GR20: practical advice after my crossing
Preparing for the GR20 isn't just about choosing a pack and booking your nights. The terrain, the heat, the descents, the weight of your pack and the back-to-back days completely change the experience. Here is the advice I keep after our North–South crossing in 12 days.
Before you set off
Fitness level
The GR20 above all demands the ability to start over several days in a row. One good day on its own isn't enough: you have to absorb the climbs, the descents, a loaded pack and the fatigue that builds up.
Endurance
Get used to walking for a long time, not just fast. The days can last far longer than the distance might suggest.
Descents
Your knees and ankles work enormously hard. Punishing descents are often more wearing than the climbs.
Loaded pack
Test your pack in real conditions. The same route feels nothing alike with 8 kg or 13 kg on your back.
Elevation, not distance
Reckon on 1,000 to 1,500 m of climbing and just as much descent per stage. It's this cumulative total, far more than the kilometres, that creates the real fatigue of the GR20.
Stringing the days together
The difficulty isn't a single stage, it's repeating it. The body shrugs off day 1 without trouble; it's holding out until day 12 that you prepare for in advance.
Start early
Allow 3 to 4 months of preparation with long outings and regular elevation gain. The GR20 doesn't forgive patchy fitness.
Useful preparation: long hikes, walking with elevation gain, cycling, light strength work, and above all outings with a loaded pack.
Terrain
The real difficulty of the GR20
The north is more technical, more rocky, steeper. The south looks more rolling, but it wears you down with distance, heat and accumulation. Never judge a stage by its distance alone.
North
More rock, more sections where your hands come in handy, slabs and footholds that call for a sure foot. It's the most technical and most striking part of the route.
South
Less technical at times, but rarely easy. The kilometres pile up on an already tired body, the heat hits harder, and the mental side takes up a lot of room.
Technical sections
In the north, some sections call for your hands, a cool head and no fear of heights. It isn't rock climbing, but it's no longer simple walking either.
Changeable weather
At altitude the weather turns fast: fog, rain, afternoon thunderstorms in summer. A stage that's easy in the sun becomes serious in a storm on wet rock.
Cumulative elevation
Over the whole route, you top 10,000 m of climbing. It's this accumulation, day after day, that sets the GR20 apart.
Worth keeping in mind: the GR20 is regularly cited among the most demanding GR trails in Europe. It isn't a rolling hike, but a true mountain trek that calls for a sure foot on certain sections.
North–South or South–North
Which direction to walk the GR20?
My takeaways are based on the North–South direction. You dive straight into the hard part, but you tackle the big difficulties while you're still fresh. In the South–North direction, the build-up in difficulty is more gradual, with a more technical finish.
North–South (the classic direction)
The most-walked direction. You tackle the north's most technical stages while still fresh, and finish on a more rolling south. The start is brutal from the very first days, but the difficulty eases as fatigue sets in.
South–North
The build-up in difficulty is more gradual: you find your legs on the south before taking on the technical north. The downside is saving the hardest part for the end, when the body has already absorbed several days. A less frequented direction.
My take: North–South still makes a lot of sense if you're ready physically and mentally. If you want a more gradual start, South–North is worth considering.
Hydration
Water and resupply
Heat changes everything. You have to anticipate water before you're in the thick of it, check the possible points, and not rely on improvisation alone. Resupply spots exist, but they vary in choice, price and opening hours.
How much to drink
In summer, reckon on 2.5 to 3 L of water a day, more on the ridges and the long exposed climbs. The classic mistake: waiting until you're thirsty. Sip regularly from the start so you never fall behind on hydration.
Where to refill
Refuges and sheepfolds are the most reliable water points. At altitude, springs and streams are common early in the season but can dry up at the height of summer. Simple rule: never leave a refuge without full bottles.
Treating water
For spring or stream water — especially downstream of herds and sheepfolds — a filter or purification tablets save you from a nasty stomach surprise hours from any help.
The driest stages
The ends of the day and the ridge sections heat up fast, including in the supposedly milder south. Anticipate water before starting the climb, not at the summit when your bottles are already empty.
Electrolytes
In strong heat, water alone isn't enough: electrolyte tablets or a little salt limit the cramps at the end of a stage, the typical trap on long days.
Food resupply
Sheepfolds and refuges sell things to top up (cheese, charcuterie, drinks, sometimes a meal), but the choice, prices and opening hours vary a lot. Always keep a buffer of bars and dried fruit.
My rule on the trail: set off with a real reserve rather than betting on the next water point. On the hottest stages of August, 2.5 to 3 L at the start wasn't too much.
Evening life
Refuges, sheepfolds and accommodation
Book when it's necessary, but keep in mind that comfort varies a lot. Meals aren't always filling enough, showers and toilets aren't the same everywhere, and late arrivals can make recovery harder.
Worth remembering: accommodation isn't just a night's sleep. It's also recovery, water, the meal, morale and getting ready for the next stage.
Bookings
Preparing your nights on the GR20
Refuges, PNRC tents, bivouac, confirmations and a safety margin: I've gathered the essentials to avoid nasty surprises.
Pack and equipment
Gear
The principle is simple: carry only what gets used often, protects against a real risk or replaces several items. The full breakdown is on the gear page.
Real cost
Budget
Your budget depends above all on the gear you start with, transport, accommodation and the way you eat. I've put the detailed breakdown on a dedicated page to keep the practical advice readable.
Classic pitfalls
Mistakes to avoid
Pack too heavy
Every extra kilo becomes a real debt on the climbs, the descents and the technical sections. Weigh your pack before leaving and cut the superfluous: aiming for 8 to 10 kg excluding water changes everything.
Brand-new shoes
The GR20 isn't the place to discover that a pair rubs or lacks grip. Put around fifty kilometres on them, uphill and downhill alike, before you set off.
Underestimating the south
Less technical doesn't mean easy. The distance, the heat and cumulative fatigue do their work: many crack in the south, not in the north.
No margin
Meals, weather, aches, schedules: you have to accept that the plan will change. Always keep a little flexibility and some food in reserve.
Neglected recovery
Eating, drinking, sleeping, drying your kit and getting ready for the next day are part of the stage. A bad night is paid for in full on the morning climb.
Poorly managed water
In summer, waiting until you're thirsty is already too late. Drink regularly, add electrolytes in strong heat, and top up at every reliable point.
Setting off too late
In summer, thunderstorms often break out in the afternoon. Leaving early means walking in the cool, avoiding wet rock and arriving before the bad weather.
Neglected descents
They're the ones that wear out your knees and cause the falls. Poles and a cautious pace beat a descent taken at speed on broken ground.
Unprepared GPX track
The waymarking is good, but fog or fatigue blur the landmarks. A GPX track loaded offline on your phone prevents many a wrong turn.
The pitfall that comes up most: setting off with a pack that's too heavy and shoes that aren't broken in. Sort out these two points and you avoid half the trouble on the GR20.
Complementary guides
Going deeper into preparation
To keep this page readable, I've split off the topics that deserve their own guide: stage planning, season, bookings and common mistakes.
12 days or 16 days
The stage plan decides everything else: daily pace, recovery, budget and the number of nights to book. 12 days is intense but coherent; 16 days leaves more room to breathe.
When to go
Late snow in June, strong heat and storms at the height of summer, packed refuges in high season: every month has its trade-offs. The right window depends on what you're willing to face.
Refuge bookings
From now on, everything goes through the Park's official platform, refuge and bivouac alike. Understanding when bookings open and keeping a margin stops you from blocking your whole itinerary.
GR20 checklist
The last safety net before setting off: pack, clothing, GPX track, first-aid kit, documents and food. Worth going through point by point the night before so you forget nothing.
Mistakes to avoid
The pitfalls that cost dearly on the trail: pack too heavy, poorly managed water, underestimated weather, descents and GPX. Knowing them in advance is already half the work.
My advice
My final piece of advice
The GR20 takes serious preparation, but you shouldn't try to control everything. Good fitness, a sensible pack, tested gear and a real ability to adapt count as much as the schedule planned on paper. The day the weather, fatigue or a full refuge upends your plan, it's that flexibility that makes the difference.
The body first
You don't need to be an athlete, but real physical preparation over several months remains the best investment. It's what lets you enjoy the scenery instead of surviving day to day.
Light and tested
A lightened pack and gear you've already proven beat the latest fashionable kit discovered on the trail. Nothing new on the day you set off.
Some humility
The mountain decides. Knowing when to slow down, cut a stage short or wait out a storm isn't a failure: it's what brings everyone back down.