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GR-25Long Distance Trail (GR)·Linear
GR-25. Etapa 03. San Román de San Millán-Zalduondo
San Millán, Biscay
Moderate33.8/100Year-round
Distance
19.8 km
Est. duration
5h 35min
Elevation gain
+381 m
Elevation loss
-375 m
Highest point
832.7 m
Lowest point
571.3 m
Average elevation
682 m
Elevation profile
Flat (≤1%)Gentle (1–5%)Steep (5–10%)Extreme (≥10%)
Flat (≤1%)
Gentle (1–5%)
Steep (5–10%)
Extreme (≥10%)
Critical Segments
Demanding Climb
CAT 4
km 9.6 · 0.9 km Distance
13% Avg
656m – 770mSlope28% Max
RiskHIGH
Demanding Climb
km 12.4 · 0.7 km Distance
10% Avg
766m – 832mSlope24% Max
RiskMEDIUM
Dangerous Descent
km 1.8 · 0.8 km Distance
11% Avg
638m – 722mSlope16% Max
RiskMEDIUM
Demanding Climb
km 0.2 · 0.7 km Distance
8% Avg
617m – 671mSlope11% Max
RiskMEDIUM
Demanding Climb
km 1.0 · 0.7 km Distance
7% Avg
671m – 722mSlope17% Max
RiskLOW
Dangerous Descent
km 14.9 · 0.7 km Distance
10% Avg
745m – 815mSlope17% Max
RiskLOW
Demanding Climb
km 8.6 · 0.6 km Distance
7% Avg
620m – 663mSlope12% Max
RiskLOW
Dangerous Descent
km 15.6 · 0.4 km Distance
6% Avg
721m – 742mSlope8% Max
RiskLOW
7-Day Forecast
Slope distribution
Flat (≤1%)18%Gentle (1–5%)44%Steep (5–10%)25%Extreme (≥10%)13%
Child-friendlyNo
Pet-friendlyNo
- 👟Trail running shoesFootwearRecommended
- 💧Carry 4–5 L (no water sources on route)WaterEssential
- 🧴Sunscreen recommendedSun protectionRecommended
- 🗺️GPS or offline route downloadNavigationEssential
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About this trail
Senderos de Gran Recorrido (GR)
| Start municipality | San Millán |
| Region | Biscay |
| Source | Federación Española de Deportes de Montaña y Escalada (FEDME) |
| Start | 42.86510, -2.31271Open in maps |
| End | 42.88553, -2.34592 |
| Track points | 435 |