Moelwyn Mawr and Moelwyn Bach Circular

A hard circular mountain walk of 6.3 miles starting and finishing at Cwmorthin Car Park outside Tanygrisiau, taking in two summits, Moelwyn Mawr (around 770 m) and Moelwyn Bach (around 710 m), with roughly 2,444 ft of climbing. Depending on how you track it, the connected line through the full sequence can measure nearer 6.8 miles.

• Cwmorthin Car Park and the Cwmorthin valley, following the western shore of Llyn Cwmorthin
• The ruined Capel Rhosydd and the Conglog Slate Quarry workings
• A sustained ascent to the summit of Moelwyn Mawr
• A rocky ridge descent over Craigysgafn to Bwlch Stwlan
• The short, steep pull up Moelwyn Bach
• Descent to Llyn Stwlan and the Stwlan Dam, then the access road and path back to the car park

This is proper mountain walking rather than a low-level stroll. Expect steep, unrelenting ascents on grass, spoil and rock, and a steep rocky, mildly scrambly descent between Moelwyn Mawr, Craigysgafn and Bwlch Stwlan where hands may be needed and a head for heights helps. Lower sections through Cwmorthin can be boggy, and some paths are faint, so navigation skills and the ability to keep a line in poor visibility are important. Sturdy boots, waterproofs, food and water, and a map and compass you can use are sensible.

The payoff is two summits in a compact loop, with wide mountain views across the ranges and out towards the coast on clear days, plus the dark water of Llyn Cwmorthin below and Llyn Stwlan held in its bowl beneath the ridge. The valley floor is dense with slate-quarrying remains, including the shell of Capel Rhosydd and the Conglog and Rhosydd workings, giving the first and last miles a strong industrial character before the ground turns to open mountain.

The loop is best in settled, dry conditions with clear air, when the ridge is grippy and the summit views open up; late spring through early autumn generally offers the longest days and driest ground. Wet, windy or low-cloud days make the Craigysgafn section slippery and the faint paths harder to follow, and winter can bring snow and ice that demand more experience and equipment. Dogs should be kept under close control throughout, as the route crosses rough mountain and grazing land with quarry ruins, steep drops and uneven rock.

You get two summits, quarry heritage and big views for a fairly short distance, but the price is steep climbing, an exposed rocky descent, boggy ground and route-finding. If you want a gentler day, choose a lower valley walk instead; if you are confident on mountain terrain, this is a rewarding half-day round.