Grand Raid de La Reunion
La Diagonale des Fous
Saint-Pierre → Saint-Denis
Race guide
Updated 19 July 2026
La Diagonale des Fous — 'The Trail of the Crazies' — is one of the most revered and brutal ultra-trail races on the planet. Starting in Saint-Pierre on the southern coast of Réunion Island and finishing 180 km later in Saint-Denis to the north, the race crosses the volcanic interior of the island with 10,007 m of cumulative elevation gain and a high point of 2,489 m. The course threads through three of Réunion's iconic cirques — Cilaos, Mafate and Salazie — along with the volcanic massif of the Piton de la Fournaise approaches, dense tropical forest, and razor-sharp ridgelines. With a 72-hour overall cut-off and checkpoints spread across terrain that is roadless for long stretches, this is not simply an ultra — it is a sustained mountain adventure where logistics, navigation, heat management and mental resilience matter as much as fitness.
Course & Terrain Overview
The route climbs almost immediately from the coast at Saint-Pierre (3 m elevation) into the island's rugged interior. By the time runners reach Notre-Dame de la Paix at 37 km, they have already ascended to 1,775 m; by Cilaos at 67 km they are at 2,183 m. The terrain is relentlessly technical — volcanic rock, exposed roots, narrow single-track ridges, and steep ravines. Réunion's trails are seldom runnable for long stretches; expect to hike hard on the climbs and to pick your footing carefully on loose, rocky descents. From Cilaos the route drops sharply to Marla (1,195 m at 79 km) before climbing back into the Mafate cirque to Grand Place at 1,873 m by 96 km. The cirque of Mafate is entirely roadless and only accessible on foot — there is no escape route between Marla and Maido. After Roche Plate (844 m, 107 km) the course grinds back up to Maido at 2,116 m (crew point, 116 km) before descending toward Saint-Denis, passing Sans Souci, Grande Chaloupe and Le Colorado before the finish at Saint-Denis La Redoute at 49 m.
Decisive Climbs & Descents — Where the Race Is Won or Lost
Three sections define the race. The first is the opening climb from Saint-Pierre to the plateau around Notre-Dame de la Paix and on to Mare à Boue (1,854 m, 50 km) — runners who go out too hard in the opening night will pay dearly in the cirques. The second is the crossing of the Cirque de Cilaos and the ascent and descent into Mafate: the drop from the Cilaos plateau to Marla (79 km) and the brutal re-climb to Grand Place (96 km) at night is where many races unravel. The third decisive section is the Maido climb from Roche Plate (844 m) at 107 km up to 2,116 m at 116 km — arriving at Maido before the 10:00 Saturday cut-off is a key survival benchmark. Runners with aspirations of finishing comfortably must bank time at Cilaos (cut-off 15:30 Friday); those arriving late to Cilaos will face a relentless chase against cut-offs through Mafate and are statistically unlikely to finish. The final 25 km from Le Colorado (170 km) to Saint-Denis is deceptively demanding on exhausted legs, descending from 426 m to the finish — do not coast it.
Pacing & Race Strategy
Start conservatively. The first cut-off at Domaine Vidot (23 km) closes at 03:30 on Friday, meaning the race typically starts mid-evening on Thursday. Many runners arrive at Cilaos (67 km, cut-off 15:30 Friday) with 15–18 hours elapsed — building a buffer of at least 90 minutes on the Cilaos cut-off is the single most important strategic goal for mid-pack runners. Use the crew point at Cilaos to change shoes, address any foot care, take a hot meal, and if you have a buffer, a 20-minute sleep can pay dividends through the Mafate night. Maido (116 km, crew point, cut-off 10:00 Saturday) is the second critical crew meeting; arriving here with 30–60 minutes in hand sets up a controlled finish. The section from Possession/Grande Chaloupe (155 km, cut-off 21:30 Saturday) to Le Colorado (170 km, cut-off 06:30 Sunday) covers only 15 km but includes significant climbing on broken legs — do not underestimate it. Plan your sleep strategy before the race: most finishers sleep between 30 and 90 minutes total; skipping sleep entirely through the second night is rarely successful.
Fuelling & Hydration
The gap between checkpoints can exceed 17 km in the Mafate cirque, and conditions range from cool mountain ridges at 2,000 m+ to humid tropical gullies at below 1,000 m. Carry a minimum of 1.5 litres of water capacity at all times and be prepared for your sweat rate to swing dramatically. Electrolyte loss is significant in the lower, humid sections — salt tablets or electrolyte drink mixes are essential from the opening hours. Crew points at Cilaos (67 km), Maido (116 km), Possession/Grande Chaloupe (155 km) and the finish allow access to drop bags and crew support; plan your real-food drops here, as hot rice, soup, or noodles at Cilaos and Maido are invaluable for morale and energy through the long nights. Between crew points, rely on a mix of gels, bars and real food available at the manned checkpoints. Don't neglect eating during the first night — many runners lose their appetite but the climbs ahead demand calories be in the system before the onset of fatigue.
Conditions & What to Expect
La Diagonale des Fous takes place in October, placing it in the transition between Réunion's dry austral winter and the approaching cyclone season. Conditions are highly variable: the coastal start can be warm and humid (25–30 °C), while ridgelines above 2,000 m can be cold, windswept, and wet. Fog and low cloud are common on the high plateau sections and through Mafate at night. Rain can transform volcanic trails into slick, treacherous surfaces extremely rapidly. Carry a mandatory waterproof jacket, warm layer and headlamp — these are not optional. The second night (Friday to Saturday) spent crossing Mafate is typically the coldest and wettest section of the course; many runners suffer from hypothermia in the cirque when temperatures drop and exhaustion sets in. Sun protection and sunglasses are equally important for the exposed ridgeline sections during daylight hours. Plan your kit to layer effectively across a 60–72 hour window where temperatures can swing by 20 °C or more.
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Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-05) · official source
0 km · 3 m · Thu 22:00
14 km · 619 m · Fri 01:30
33.4 km · 1689 m · Fri 07:00
45.4 km · 1997 m · Fri 10:30
55.6 km · 1593 m · Fri 13:00
65.1 km · 2009 m · —
67.6 km · 2221 m · Fri 17:30
70.5 km · 2326 m · —
76.4 km · 1320 m · Fri 20:30
80.4 km · 1120 m · Sat 01:00
84.1 km · 1131 m · —
85.7 km · 1435 m · —
87 km · 1715 m · —
92.9 km · 1540 m · —
93.6 km · 1722 m · Sat 06:00
95.8 km · 1820 m · Sat 07:00
102.2 km · 1509 m · —
104.2 km · 1199 m · —
107.6 km · 748 m · Sat 11:30
111.1 km · 615 m · —
116.2 km · 685 m · Sat 16:30
118.7 km · 957 m · —
122.2 km · 1676 m · —
123.7 km · 1954 m · Sat 20:30
140.3 km · 334 m · Sun 00:15
147.7 km · 656 m · Sun 03:00
153.7 km · 395 m · —
154.9 km · 297 m · Sun 06:30
164.3 km · 192 m · Sun 09:00
168.8 km · 379 m · —
173.6 km · 699 m · Sun 13:30
177.6 km · 354 m · —
180.6 km · 49 m · Sun 16:00
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