|Location||Snowdonia, North Wales|
|Type||natural lake, reservoir|
|Primary outflows||Afon Dulyn|
|Basin countries||United Kingdom|
|Surface area||33 acres (13 ha)|
|Max. depth||189 ft (58 m)|
The lake covers an area of only 33 acres (130,000 m2), yet is extremely deep - it reaches to a depth of 189 feet (58 metres). Less than a kilometre to its south lies the smaller Llyn Melynllyn.
The lake has a dam, originally built in 1881, to increase its water capacity, but it has been altered several times since. As a reservoir Dulyn (along with Melynllyn) provides water for the town of Llandudno. The pipes cross the River Conwy at Tal-y-Cafn bridge.
In June 1284 the lake was the setting for the court of King Edward I of England for victory celebrations, following his defeat of Llywelyn ap Gruffudd, with an Arthurian theme, including the King’s 45th Birthday
A number of superstitions are connected with the cwm, which has also been the site of a number of aeroplane crashes.
- Marc Morris. 2009. A Great and Terrible King. London: Windmill Books. 364.
- The Lakes of Eryri by Geraint Roberts, Gwasg Carreg Gwalch, 1985
- "Douglas C-47B 43-48473 of the 27th Air Transport Group flew into the cliffs above Llyn Dulyn in the Carneddau while flying form Le Bourget to Burtonwood on the 11th November 1944". www.peakdistrictaircrashes.co.uk. Retrieved 7 October 2017.
- "The Lakes of North Wales" by Jonah Jones, Whittet Books Ltd, 1987
- "The Lakes of Eryri" by Geraint Roberts, Gwasg Carreg Gwalch, 1985
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