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.
Pen-y-fan Pond Pen-y-fan Pond Pen-y-fan Pond is a man-made reservoir built around 1794-6 as part of the engineering works for the Crumlin Arm of the Monmouthshire Canal. The reservoir was used to maintain the water level in the canal. The reservoir is formed by a large earth dam with stone facings, forming banks on three sides of a gentle slope. The outlet to the canal feeder forms a stone-lined, oval tunnel and a valve chamber is set into the bank above. Pen Y Fan Pond Country Park features the reservoir, and provides a circular walk around the lake, and minimal facilities for