Diagonale des Fous 2026: A Detailed Look at La Réunion’s Mythical Course

The flagship race of the Grand Raid de La Réunion, the Diagonale des Fous remains one of the toughest, wildest and most fascinating ultra-trails on the planet. For 2026, the organizers once again offer a punishing route of nearly 181 kilometers crossing the island from south to north, from the shores of the Indian Ocean to the iconic Stade de La Redoute. Endless climbs, brutal descents over volcanic rock, exposed traverses and stifling humidity: here is the course, section by section.

1. The Southern Launch: From Saint-Pierre’s Fervor to the High Pastures (km 0 ➔ km 55.6)

It all starts on the seafront in Saint-Pierre (Ravine Blanche / Place Salahin). Fueled by the electric atmosphere and the Réunion crowd, the field heads along Boulevard Hubert De Lisle toward the Terre Sainte district. This flat, fast opening stretches out the ribbon of headlamps before the first slopes begin.

The scenery changes as soon as runners reach Chemin de la Croix Jubilé: the trail heads onto dirt tracks through sugar-cane fields. The climb continues to Domaine Vidot (km 14, 649 m), the first major checkpoint and medical station. From there, the course climbs into the highlands via the Sentier des Foulées de la Fraise, then crosses ravines and forests to Notre-Dame de la Paix (km 33.4, 1,686 m).

After a steep crossing of the Grande Ferme pastures and a detour around Piton Sec via the Volcan trails, the route reaches the Nez de Bœuf area before descending toward Chalet des Pâtres. Runners then cross the RN3 to reach the first major strategic stop of the night: Mare à Boue (km 55.6, 1,604 m).

2. The Island’s Roof and Salazie’s Green Kingdom (km 55.6 ➔ km 80.6)

From Mare à Boue, the race gets serious. The GRR2 takes runners on a long, often muddy climb through the highland forest of Bois de Couleurs to Coteau Kerveguen (km 65.1, 2,187 m). The route then heads toward the course’s highest point, the Croisée Coteau Kerveguen / Caverne Dufour (km 67.6), skirting the 2,500-meter mark at the foot of Piton des Neiges.

Then comes the brutal drop:

Cap Anglais (km 70.5): A technical, treacherous and slippery descent where total concentration is essential.
Gîte de Bélouve (km 76.4, 1,502 m): A spectacular window opens onto the lush ramparts of the Cirque de Salazie.
Hell-Bourg (km 80.6, 995 m): The course’s first aid station. Runners collect their first drop bag, a hot meal and essential medical attention before heading deeper into the island’s wild interior.

3. The Hell and Magic of the Cirque de Mafate (km 80.6 ➔ km 123.9)

Leaving Salazie via the Bras Marron footbridge and the hamlet of Mare d’Affouches, the course reaches Plaine des Merles (km 93.8). This is the gateway to the legendary Cirque de Mafate, accessible only on foot or by air.

The route enters Mafate via the magnificent Sentier Scout (km 96). Runners plunge down the GRR3, cross the Bras Bémale and follow the spectacular « Deux Fesses » ridge, now protected by a guardrail. The course then strings together a rare succession of punishing ups and downs:

Îlet à Bourse (km 104.4), via the Bras d’Oussy footbridge.
Grand Place les Bas (km 107.8), followed by the steep climb to Grand Place les Hauts.
Roche Ancrée (km 111.3), with a ford crossing of the Rivière des Galets and the grueling switchback climb toward Roche Plate.
Roche Plate / Plateau Cerf (km 118.9).

To escape this verdant trap, runners must face the course’s monster: the passage through La Brèche followed by the wall of Ti Col / Maïdo (km 122.4). A near-vertical climb along the cliffside, taking runners from 1,200 m to more than 2,000 m above sea level.

4. The Long Descent Toward the Coast (km 123.9 ➔ km 155.1)

From Maïdo (km 123.9), an endless descent through the Bois de Couleurs takes runners out of the mountains, through the Sans Souci district and on to Îlet Savannah (km 140.5, second aid station).

After recovering from their Mafate ordeal, runners tackle the Halte-Là plateau and Chemin Ratinaud (km 147.9). This is where they reach the Sentier de la Kalla, notorious for its slippery rocks and stifling profile, before emerging into the urban area of La Possession at Place Festival (km 155.1).

5. The Final Test on the Way to La Redoute (km 155.1 ➔ km 180.8)

Even with less than 30 kilometers to go, the Grand Raid offers no favors:

Le Chemin des Anglais (Chemin Crémont) (km 155.1 ➔ km 164.5): This historic trail, paved with large, abrasive and heat-soaked volcanic stones, overlooks the sea all the way to La Grande Chaloupe.
Saint-Bernard & La Montagne (km 169): A steady climb through woodland and trails leads to Colorado (km 173.8, 682 m), the final major checkpoint.
Les Rampes de la Montagne & Belvédère de la Vigie (km 177.8): Runners begin the final descent, steep and technical, plunging straight toward the Réunion capital.

The Finish: Stade de La Redoute (km 180.8)

After dozens of hours of effort, pain and wonder, salvation lies at the end of Saint-Denis’s stadium track, sealing the Diagonale des Fous finisher’s status as a « Survivor ».