Cwm Idwal is a hanging valley in the Glyderau range in N.Snowdonia. Its main interest is to hill walkers & rock climbers but is also of interest to geologists & naturalists. Cwm Idwal is a spectacular product of glaciation, surrounded by high crags, screes, moraines and rounded rocks, with a lake on its floor (Llyn Idwal). Given its elevation and N. facing aspect, Cwm Idwal is the most southerly place in Britain where Arctic plants such as Moss Campion & Alpine Saxifrages can be found.
In 2005 Cwm Idwal, Wales was ranked the 7th greatest natural wonder in Britain.