Llyn Dulyn is one of the remotest lakes in Snowdonia. It is a classic cwm or cirque where snow during the Ice Age accumulated and was coverted to ice moving on as a glacier eastwards towards the Conwy Valley, to join the Conwy Valley glacier on its journey north. During the second world war in 1943 an Anson EG110 aircraft crashed above Cwm Dulyn. It is a story of great heroism how pilot officer Ken Archer somehow in total darkness and seriously injured made his way down the rocks at the side of Llyn Dulyn to get help. It took him 17 hours to get down the mountain . A search party of 35 men then searched all night, eventually the wreck was reached but it was too late for two of the crew only one surviving the cold and by then snow. The full moving story is related in the book "No landing place" by Edward Doylerush 1985 and is one of many such crashes in Snowdonia recorded in a series of books by the author.