Portugal · Northern Portugal
Distance
100 km
Date
Entry fee
€100
€ / km
€1.00
Grande Trail Serra d'Arga 100km: Portugal's Night-Start Granite Test, Measured
Grande Trail Serra d'Arga (GTSA) 100 km is a trail race held on October 2–4, 2026 in Northern Portugal's Serra d'Arga mountains, Viana do Castelo district.
The 100 km distance starts at 22:00 on October 2 — a night start that places runners in darkness for their first 6–10 hours. The course covers 100 km with 4,151 m of gain (41.5 m/km) across granite ridges, technical singletrack, and preserved rural villages. Three of the five major climbs hit maximum gradients above 50%, and nearly 10 km of the course sits above 15% gradient — genuine hiking and scrambling terrain.
The defining descent — 699 m over 10.3 km starting at km 75 — is one of the longer sustained drops in the DTR database. October in Northern Portugal averages 15 rainy days; wet granite amplifies the technical demands on a course where descents average −10.7%. Entry costs €1.00/km — €100 for a UTMB Index 100K qualifier. Porto (OPO) and Vigo (VGO) airports are both 61 minutes by road.
Organized by Carlos Sá since at least 2014, GTSA 100 km drew 130 finishers in 2024 — up 44% on 2023 — with a cap of 200 runners. It suits experienced mountain ultra runners comfortable with night starts, technical granite terrain, and a course that saves its hardest 10 km for last.
Elevation and Terrain
Total Meters
4,151m
D+/KM
41.5m/km
For context, the Tor des Géants 330 loop has 73 D+/km.
Avg Uphill Gradient
10.9%
Avg Downhill Gradient
-10.7%
Uphill gradient distribution
| 2–5% | 11.1 km | |
|---|---|---|
| 5–10% | 10.4 km | |
| 10–15% | 7.5 km | |
| 15–20% | 5.3 km | |
| 20%+ | 4.7 km |
Route Profile
AnalysedTerrain breakdown
| 39.6% | Uphill |
|---|---|
| 22.6% | Flat |
| 37.8% | Downhill |
Terrain
Grande Trail Serra d’Arga – 100 km 100km Top Climbs
Top Climbs
| 1 | 4.0 km · 427 m gain starts km 48 · avg 10.8% · max 51.4% |
|---|---|
| 2 | 3.8 km · 424 m gain starts km 92 · avg 11.2% · max 51.7% |
| 3 | 8.3 km · 402 m gain starts km 25 · avg 4.8% · max 37.5% |
Top descents
| 1 | 10.3 km · 699 m drop starts km 75 · avg -6.8% · max -36.2% |
|---|---|
| 2 | 5.3 km · 444 m drop starts km 52 · avg -8.3% · max -30.8% |
| 3 | 4.1 km · 415 m drop starts km 95 · avg -10.0% · max -47.4% |
Why the GTSA 100km Is Harder Than 4,151m Suggests
How hard is the Grande Trail Serra d'Arga 100km?
▼
Seriously demanding throughout. At 41.5m/km elevation density, 10.86% average uphill gradient, and just 22.6% flat terrain, the GTSA 100km delivers sustained gradient pressure with minimal recovery. Three climbs breach 50% maximum gradient, the final 8km features the race's hardest wall followed immediately by its steepest descent, and the night start means the opening 6–10 hours run in darkness.
The Grande Trail Serra d'Arga 100km's Qualification Status
Is Grande Trail Serra d'Arga 100km a UTMB qualifier?
▼
Yes. The GTSA 100km is a UTMB Index 100K category race and ITRA certified.
Portuguese Mountain Value: The Grande Trail Serra d'Arga 100km Entry Fee
How much does it cost to enter Grande Trail Serra d'Arga 100km?
▼
€100 standard entry — €1.00 per kilometre — for a UTMB Index 100K qualifier. Entry rises to €105 from September 12, 2026. One of the most affordable 100K qualifier entries in Europe.
When does the 2026 Grande Trail Serra d'Arga 100km take place?
When does the 2026 Grande Trail Serra d'Arga 100km take place?▼
October 2–4, 2026. The 100km starts on the evening of October 2 at approximately 22:00. Bib collection runs 17:00–22:00 at Praça do Conselheiro Silva Torres, Caminha.
Porto or Vigo: Getting to Grande Trail Serra d'Arga 100km
Which airport should I use for Grande Trail Serra d'Arga?
▼
Porto (OPO) and Vigo (VGO) in Spain are both approximately 61 minutes by road to the race area. Porto has better international connections; Vigo is useful if travelling from Spain. Good public transport exists via Porto → Viana do Castelo → Caminha.
Grande Trail Serra d’Arga – 100 km 100km GPX
Getting to Grande Trail Serra d’Arga – 100 km
Nearest airport
Porto (OPO) / Vigo (VGO)
Notes
Start: ~1–1.5 hrs (OPO) or ~1 hr (VGO) by car to Caminha / Public transport: good (train Porto→Viana do Castelo/Caminha) + taxi/bus last-mile / Accommodation: good supply in Caminha/Vila Praia de Âncora/Viana do Castelo; book early
