Llyn Cau

The Minffordd Path is widely regarded as the most dramatic route on Cadair Idris — a path that begins in the Tal-y-llyn valley at the National Trust car park at Minffordd (where the Minffordd Hotel sits at the valley junction) and ascends through ancient sessile oak woodland before emerging dramatically into the hanging cwm of Llyn Cau. The transition from enclosed woodland to open cwm — with the vertical crags of Cadair Idris's south face rising 400 metres above the lake — is one of the most sudden and overwhelming landscape changes in Snowdonia. The path to Llyn Cau is approximately 2.5 miles from the car park with 400 metres of ascent; the full Minffordd Path to the Cadair Idris summit (Penygadair, 893 m) continues from the lake by scrambling up a rocky ridge to the rim of the cwm, then following the summit ridge — total 5–7 hours from the car park.

Llyn Cau sits in one of the most perfectly formed glacial cwms (cirques) in Wales — a horseshoe-shaped bowl carved by a glacier that occupied the cwm during the last Ice Age (ending approximately 10,000 years ago). The lake is enclosed on the north, west, and east sides by near-vertical crags that drop almost directly into the water, while the south side (where walkers arrive from the Minffordd Path) is a moraine barrier. The enclosing walls of rock rise approximately 400 metres above the lake surface to the summit ridge of Cadair Idris — creating an atmosphere of total enclosure and scale that is difficult to convey in photographs. The lake itself is dark (it receives little direct sunlight due to the enclosing crags), cold, and deep — deep enough that its bottom has not been charted with certainty in all areas. In calm conditions, the still water perfectly mirrors the surrounding crags. The combination of vertical rock, dark water, and mountain scale makes Llyn Cau one of the most viscerally impressive mountain lakes in Wales.

Llyn Cau is swimmable — the water is clear and relatively unpolluted — but it should be treated with respect. The lake is cold even in summer (water temperature rarely exceeds 12–14°C even in August), deep, and in a serious mountain environment where emergency assistance would take considerable time to arrive. Wild swimmers should never swim alone, should enter the water slowly to acclimatise, and should not swim out into the centre of the lake far from the shore. The approach to the water's edge is rocky and uneven. The atmosphere of Llyn Cau — enclosed by vertical crags on three sides — adds a psychological dimension to the experience that some swimmers find overwhelming rather than exhilarating. For experienced cold-water swimmers with appropriate knowledge and companions, Llyn Cau offers a genuinely extraordinary mountain swimming experience. For casual swimmers or those new to wild swimming, Llyn Padarn at Llanberis (much more accessible, with a lifeguard at peak season) is a more suitable option.

Cadair Idris ("Chair of Idris" — Idris being a legendary giant or warrior-bard of Welsh mythology) has a rich legendary tradition that extends to Llyn Cau. The most widely told legend holds that anyone who spends the night on the summit of Cadair Idris will wake either a poet or a madman (or will not wake at all). The mountain's dramatic character — the steep crags, the enclosed cwms, the sudden mists — clearly gave rise to a sense of supernatural power. Llyn Cau itself is sometimes associated with a lake monster or supernatural creature in Welsh folk tradition, and the deep, dark, enclosed nature of the lake makes such legends entirely comprehensible to anyone who visits. The mountain name also appears in some interpretations as "Cadair Arthur" — the Chair of Arthur — making it one of several locations in Wales associated with the Arthurian legends. The combination of Welsh mountain mythology and genuinely overwhelming mountain scenery gives Llyn Cau a resonance that persists even for visitors with no interest in folklore.

The Minffordd car park sits at the junction of the Tal-y-llyn valley and the valley leading south towards Abergynolwyn. Tal-y-llyn lake — a long, narrow glacial ribbon lake in the shadow of Cadair Idris — is 2 miles from the car park and is accessible by road without any walking; it's one of the most beautiful valley lakes in south Snowdonia. The Talyllyn Railway runs from Tywyn (on the coast) to Abergynolwyn (7 miles from Minffordd) — a narrow-gauge steam railway through the valley. Castell y Bere — the ruined Welsh castle built by Llywelyn the Great in a mountain valley — is 8 miles north-east. The Mawddach Estuary and Barmouth (10 miles) complete the south Snowdonia circuit. A full two-day itinerary might combine Cadair Idris (Minffordd Path) on day one with Castell y Bere, Talyllyn Railway, and the Mawddach Estuary trail on day two.