Llyn Cwm Llwch both Pen y Fan and Corn Du and indeed from the spur of Pen Milan to its west. Llyn Cwm Llwch Llyn Cwm Llwch () is a small lake or pool in the Brecon Beacons National Park in Powys, Wales. It is between 1 and 2 acres: much smaller than the two glacial lakes in the west of the Black Mountain (range): Llyn y Fan Fawr and Llyn y Fan Fach. It is of glacial origin, occupying a rock hollow beneath the peaks of Pen y Fan and Corn Du in the central Brecon Beacons. It is drained by the
Pen y Fan mountain is used by the military as part of the selection process of the UK's Special Forces personnel. Three soldiers who died after collapsing in the field in July 2013 were believed to have been climbing the mountain (see "Fan Dance") while undergoing Special Air Service selection. The peak is a major objective in the Beacons Way, a long distance footpath which passes from east to west across the massif, and is open to all walkers. There is well made, evenly graded footpath from the Storey Arms on the A470, which is 1500 feet below, allowing for safe access during