GR20 : Ten pieces of advice that you won’t hear anywhere else

Eat properly, drink plenty, prepare physically upstream, test your equipment... All good advice heard at the dawn of setting off on the GR20. All these tips should be respected. However, if they are applicable to the legendary Corsican trail, they are not specific to it. The winding trek is unique and therefore deserves tips that are its own.

We asked Guillaume Peretti, a high-level trail runner from a small village in the East of Corsica, who in 2014 lowered the record time of the trek previously held by Kilian Jornet from 32h54 to 32h. He considers the GR20 his backyard and knows every path in Corsica like the back of his hand, offering tips that you won't hear anywhere else.

Monitor your feet at all costs

"Feet are the basic working tool of the hiker on the GR20. Neglecting them is like a musician going on tour without his instruments or a stonemason going to the quarry without his chisel. The terrain is elusive, and the descents are rocky. These are not classic hiking trails. If you experience any pain or early signs of a blister, you must treat them immediately."

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Adapt your start time

In Corsica, it's customary to hit the trails at daybreak. Guillaume Peretti adds a nuance: "You need to be strategic and adapt your departure time based on the day's stage, its topography, and weather conditions. Ideally, it's best to gain altitude during the hottest part of the day and, conversely, avoid peaks during the cooler hours."

Trust a safe source regarding the weather

"Corsica is subject to a unique microclimate as it’s an island with peaks reaching over 2500 m in altitude. These are high mountain areas! Weather conditions change quickly, making it complex to predict. I trust two reliable sources: an Italian maritime weather site and Mother Nature, particularly the wind. For example, a north-easterly wind brings cool air and bad weather, while strong gusts tend to drive away the rain."

Don’t take too much water, nor not enough

Like feet, water is essential for hikers on the GR20. Guillaume clarifies: "The challenge is finding the right balance. Don’t take too much water, nor too little... Hikers are often overly cautious and carry more reserves than needed. There's no point lugging 3L or 4L in your already heavy bag when you’ll find drinking water sources along the way. Just ensure you have basic IGN map reading skills and carry an extra 0.5L as a precaution in case the spring is dry."

Do not underestimate the south part

"The northern part of the GR20 is technical and physically demanding, almost like climbing. It’s so challenging that hikers might wrongly underestimate some of the remaining stages. For example, the ridge road between the Prati refuge and the Usciolu refuge (stage 12) is very demanding with endless ridges and small bumps on steep terrain, often subject to storms. Beware, after the first three stages, you haven’t finished the GR yet!"

Evaluate the difficulty of going downhill

"People often fear the altitude gain of the GR20, but the hardest part is not the climb, it’s the descent! The real challenge isn’t reaching the peaks; it’s leaving them."

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Go off the beaten track

"To ease the descent, especially when the path is rocky and winding, I prefer slabs beside the trail as they are smoother and less traumatic. Don’t hesitate to stray slightly from the beaten path, provided the slabs are dry."

Change T-shirts during the stage

Given the rapidly changing weather conditions, Guillaume advises always carrying a spare T-shirt in your bag to change into quickly during the stage. Don’t limit yourself to one item of clothing per day.

Dry your possessions in record time

"I have a trick to dry a rain-soaked or sweat-drenched T-shirt in record time: during breaks, lay it out on a rock exposed to the sun."

Stop at a shelter whatever the cost

"Shelters are not just for sleeping or eating; they’re part of the GR20 experience. You don’t need to stop for long—five minutes to sip a beer or greet the concierge is enough. Crossing Corsica without connecting with its people would mean missing out."

For the nine things to do upon arrival at the shelter, check them out here: Read the article