Mountain bike trip in Llyn y Fan.

Llyn y Fan Fawr is a natural lake thatlies at the foot of Fan Brycheiniog, the highest peak of the Black Mountain range within the Brecon Beacons National Park.

The lake is enclosed within a rock hollow formed as a result of glacial action during the ice ages. It is drained by a stream known as Nant y Llyn whose waters flow into the River Tawe. The surface of Llyn y Fan Fawr lies at about 605 m above sea level.

The lake can be reached on foot by a 2 km walk across the moor from the minor Trecastle to Glyntawe road.