01
Maïdo - Roche Plate (Mafate)
A loop or out-and-back: a technical descent into Mafate (1,200m down), then back up to Maïdo. 18-25km, 1,500m of ascent. The classic route for practising technical descents.
Mountain running · Reunion Island
Trail Running in Reunion Island: the Grand Raid, races and best trails
From the legendary Diagonale des Fous to night races in the highlands, Reunion Island is one of the world's great testing grounds for tropical mountain running. Here's the race calendar, the best training trails, the kit you need and how to prepare for the Diagonale.
≈165km Diagonale10,200m of ascent4 races at the Grand Raid3,070m highest summit
The Grand Raid
The legendary ultra of the Indian Ocean
The Diagonale des Fous was born in 1989, the brainchild of a handful of passionate Reunion Islanders. Three decades on, the Grand Raid de La Réunion has become one of the most legendary ultra races in the world, drawing more than 6,000 runners from around the globe every year for its four races over the last weekend of October.
This page covers the lot: the four Grand Raid races in a detailed table (distance, ascent, cut-offs, who they suit), six classic training trails, how to prepare for the Diagonale, the right kit for tropical trail running and a detailed FAQ.
For registration and the official calendar, learn more about the Grand Raid on the official website: rules, compulsory kit, aid stations, qualifying points and ballots for each race.
The races
Six big races to know
The four Grand Raid races in October plus two classic races held during the year, with distance, ascent, cut-off and who they suit.
| Race | Distance | Ascent | When | Cut-off | Who it suits |
|---|---|---|---|---|---|
| Diagonale des Fous | ≈165km | ≈10,200m | 3rd week of October | 67h max | Elite and experienced runners. 50-60h for the average finisher, 24h for the fastest |
| Trail de Bourbon | ≈110km | ≈6,500m | 3rd week of October | 33h max | Experienced runners. A good first ultra in Reunion Island |
| Mascareignes | ≈75km | ≈4,100m | 3rd week of October | 20h max | An introduction to long distance, doable in a weekend |
| Zembrocal Trail (4-runner relay) | ≈65km total | ≈3,700m | 3rd week of October | Varies | Teams, a party atmosphere, ideal for a first trail race together |
| Cimasarun (Saint-Denis urban trail) | Varies by edition | Varies | Every year | - | All levels, a fun city race |
| Trail des Sables (Plaine des Sables) | Short to medium | Short to medium | Every year | - | A taste of the volcano, open to most runners |
Training
Six classic training trails
From rolling trails to technical singletrack, six classics to get your legs ready for Reunion Island's volcanic terrain.
02
Pas de Bellecombe - Piton de la Fournaise
A 12km out-and-back with 600m of ascent on sharp basalt. Ideal for getting used to the Diagonale's unique volcanic terrain.
03
Sentier Scout (Cilaos - Piton des Neiges)
The climb up Piton des Neiges from Cilaos: 12km up with 1,700m of ascent. The go-to training route for the Diagonale (it's a key section of the race).
04
Tévelave - Maïdo
Cryptomeria forest, shady trails and a steady climb. 15-20km, 1,000m of ascent. Ideal for regular training close to the coast.
05
Plaine des Cafres - Piton de l'Eau
Rolling, not very technical trails across a forested plateau. 10-15km, 400m of ascent. Ideal for speed work and easy long runs.
06
Hell-Bourg - Trou de Fer
Rolling trails through Bélouve forest. 14km out-and-back, 500m of ascent. Ancient rainforest scenery, and quiet on weekdays.
Frequently asked questions
Your questions answered
What trail races are there in Reunion Island in 2026?
The big event is still the Grand Raid in October, with four races on the same weekend: the Diagonale des Fous (≈165km, 10,200m of ascent), the Trail de Bourbon (≈110km, 6,500m), the Mascareignes (≈75km, 4,100m) and the Zembrocal Trail (a 65km relay for teams of four). The rest of the year, there's the Cimasarun (a city trail race in Saint-Denis), the Trail des Sables (Plaine des Sables), village races in every cirque and several night trail races in the cool season (June-September). For the official calendar and registration, see the Grand Raid website.
What is the Diagonale des Fous?
It's the Grand Raid's flagship race, first run in 1989: a crossing of the whole island from Saint-Pierre to Saint-Denis, through the three cirques (Cilaos, Mafate, Salazie) and over Piton des Neiges (3,070m). That's around 165km with over 10,200m of ascent, completed in 24 to 67 hours depending on the runner. It starts at night in Saint-Pierre, and the leaders reach the Stade de la Redoute in Saint-Denis the following evening. Its name means "the madmen's diagonal", and it's one of the toughest and most legendary races in world ultra-running.
How can you run in Reunion Island without entering a race?
The national park's trails are open all year, making the island one of the wildest trail running playgrounds in the world. The classic training runs are the Maïdo-Roche Plate loop, Piton de la Fournaise via Pas de Bellecombe, the Sentier Scout up Piton des Neiges and the Tévelave trails in the west. Wherever you go, stick to the safety basics: check the weather and carry water, a head torch with a spare battery, warm clothing, a whistle and a charged phone.
How should you prepare for the Diagonale des Fous?
With a long build-up (12 to 18 months for a first ultra): weekly mileage topping 80km at peak, long mountain days (40-60km with plenty of climbing) as qualifiers, specific work on technical descents, and regular night runs to get used to running in the dark. Many runners from mainland France arrive one to two weeks early to adjust to the tropical heat and the relentless climbs. The average finisher takes 50-60 hours, the fastest 24 hours, and historically 30-40% of starters drop out.
Are the trails open for unsupervised trail running?
Yes, apart from temporary closures by the authorities (cyclones, heavy rain, works). The ONF (the forestry office) website keeps an up-to-date list of closed trails, and my article on trails closed after cyclones fills in the gaps. In the dry season (May-November), almost the whole network is open. Always check before a long run: a closed trail can be a nasty surprise at kilometre 30.
What specific gear do you need for trail running in Reunion Island?
Three things matter most here: trail shoes with aggressive lugs (Salomon Speedcross, La Sportiva Bushido) for wet basalt, which gets very slippery after a downpour; a 5-12L hydration vest (Salomon Adv Skin, UltrAspire, Camelbak Octane) with a 1.5L bladder and front flasks; and an ultralight waterproof, breathable jacket (200g, Salomon Bonatti style) always in your pack for the sudden mountain showers. For the Grand Raid, the compulsory kit is listed in the race rules, so weigh and check yours before the start.
How do you register for the Grand Raid?
Registration opens on the official website, grandraid-reunion.com, in May-June for the October race. For the Diagonale des Fous, there's a ballot if demand exceeds places, you need qualifying points (ITRA system) and a medical certificate less than 6 months old confirming you're fit for ultra-endurance racing. 2026 fees are around €250-300 for the Diagonale, less for the other races. Book accommodation early: the island is full in October.
Are there night trail races in Reunion Island?
Yes, several night races take place during the year, especially in the cool season (June-September). The upsides: cooler temperatures, running under the southern stars and a special atmosphere. The downsides: technical trails are harder by head torch, and it gets cold at altitude at night (5-12°C). They're a great stepping stone for getting used to night running before an ultra like the Diagonale, which always starts at night.
What's the philosophy behind trail running in Reunion Island?
Three values keep coming up in the local trail running community: respect for the land (the national park, fragile trails, taking your rubbish home), solidarity between runners (on the Grand Raid, runners help each other out) and humility in the face of tropical mountains (the weather and the climbs can catch anyone out). Here, you're not racing against others so much as against yourself, on a one-of-a-kind playground. That spirit draws more than 6,000 runners from around the world every year.
Going further
Keep reading
- → Hiking gear for Reunion Island: with a trail running section.
- → Crossing the 3 cirques: a 5-7 day route and solid training.
- → Trails closed after cyclones: check trail conditions.
- → All Reunion Island guides.