On the western side of the Black Mountain, a stony track climbs to a glacial lake cupped beneath the great scarp of the Carmarthen Fans. This is Llyn y Fan Fach — home of Wales’s most famous folk tale.
The legend: a farmer fell in love with a fairy woman who rose from the lake. She married him on the condition he never strike her three times; he did, she returned to the water — and their sons became the Physicians of Myddfai, a real, historically documented line of medieval healers.
The walk is a steady four-mile out-and-back from the little car park at Llanddeusant, with red kites overhead and a fraction of Pen y Fan’s crowds. Carry on up to the ridgeline of Bannau Sir Gaer if you want one of the finest viewpoints in the national park.
Worth knowing
- The lake sits at around 510 metres beneath Bannau Sir Gaer (Picws Du), on the Beacons’ quiet western massif.
- The Lady of the Lake’s sons, the Physicians of Myddfai, really existed — court physicians documented from the 13th century.
- The Red Kite Feeding Station at Llanddeusant is in the same valley — feeding happens every afternoon (closed Mon–Tue) and makes a perfect double-bill.
- No facilities at the lake — take everything you need and bring it back out.