Llyn Peris is a glacial lake located in Snowdonia, near the villages of Llanberis and Nant Peris, Wales. It is named after Saint Peris, a Christian saint. This lake is surrounded by the Elidir Fawr mountain and the small village of Dinorwig. On the other side the hills of Derlwyn and Clogwyn Mawr can be found, and also a rock formations named Lady of Snowdon. Near the lake Dolbadarn Castle is found, which was built in 13th century. Arctic char can be found here, although during the construction of the power station a large quantity were removed to other lakes in the neighbouring Carneddau mountains.