Llyn y Fan Fawr outflow is to the River Tawe. Much of the land around the lake is peaty and thus wet underfoot. Llyn y Fan Fawr Llyn y Fan Fawr (Welsh: 'lake of the big peak') is a natural lake in the county of Powys, Wales. It lies at the foot of Fan Brycheiniog, the highest peak of the Black Mountain (Welsh"Y Mynydd Du") range within the Brecon Beacons National Park. Created as a result of glacial action, it is one of the largest glacial lakes in southern Wales. The lake is roughly rectangular in shape with its long axis oriented roughly north-south.
Chwarel y Fan Monmouthshire. The summit is on a thin ridge and is crowned by a cairn. On the other sides of the valleys: to the west is Pen Twyn Mawr and to the east is Black Mountain. Chwarel y Fan Chwarel y Fan is a peak in the Black Mountains in south-eastern Wales. It is the highest rise on the long ridge which extends southeastwards from Rhos Dirion. The ridge continues southeastwards to the lesser summit of Bal-Mawr whose top is adorned by a trig point at above sea level. A further 1 km southeast along the ridge is the lesser top