Marchlyn Mawr Dam is an epic road in Wales
Marchlyn Mawr Dam is a natural lake dammed to form a reservoir at an elevation of 643m (2,109ft) above the sea level, located in Gwynedd, in north-west Wales. It’s one of the highest roads of the country.
Tucked away in Snowdonia, a mountainous region in north west Wales, the road to the lake is totally paved but very narrow. The road to the reservoir is owned by the power/water company. It is possible to cycle up the road to the reservoir but a gate prevents cars from driving on the road. The final 1.8 miles are closed to private vehicles.
Starting from Deiniolen, a village in Gwynedd, at the foot of Elidir Fawr, in Llanddeiniolen Community, the ascent is 5.31km (3.3 miles) long. Over this distance, the elevation gain is 426 meters. The average percentage is 8.02 %. The maximum gradient is 12.0%.