Llyn y Fan Fach (Welsh meaning "little lake (near) the peak") is a lake of approximately 10 hectares (25 acres) on the northern margin of the Black Mountain in Carmarthenshire, South Wales and lying within the Brecon Beacons National Park. The lake lies at an altitude of approximately 1,660 feet (510 m), immediately to the north of the ridge of the Carmarthen Fans. It is the smaller of two lakes within this mountain massif: the slightly larger Llyn y Fan Fawr is about 2 miles (3.2 km) to the east.