Monte Oiz is a mountain peak at an elevation of 1.026m (3,366ft) above the sea level, located in Biscay in the Basque Country (Spain). The climb is simply terrible, going up to 20% gradients. The climb is known for its half-asphalt, half-concrete surface and irregular ramps.
There are 2 routes to reach the summit. Starting from Iurreta, the ascent is 14.7km long and the average gradient is 6.0%. And starting from Munitibar, the ascent is 8,9km long and the average gradient is 9.4%. The mountain is clearly distinguished from its surroundings, mostly because of the large antenna and the wind turbines in the top. Its location in the middle of the province and its height provides great views from the summit, from the nearby sea to the surrounding mountains. The road surface is in very good condition for the first 6km. After this it becomes a narrow corrugated concrete track, slighlty bumpy in places. Getting closer to the summit, the road conditions worsen and the slopes that loom become ever more ominous.
The climb is simply brutal, especially the last 5km with an average gradient of 11% with some sections up to 20%. Expect fog and rain often. The summit is also known as Balcón de Vizcaya (Biscay Balcony) with views over the Cantabric sea. The climb has been featured in the Spanish Vuelta race. In 1985, it was the scene of a plane crash, after a flight from Madrid to Bilbao hit the radar tower at the top of the climb in thick cloud.