Llyn Dinas is one of the many mysterious pools or lakes which have been associated with King Arthur. It is in the Snowdonia mountains in North Wales, and is close to a number of the other Welsh King Arthur sites.
The surface of Llyn Dinas reflects the Dinas Emrys which towers over it. Llyn Dinas is said to have been the site of a battle between Sir Owein, one of Arthur's knights, and a giant.
Vortigern is also supposed to have hidden the throne of Britain beneath a great stone here. And some say Merlin's treasure is buried beneath the hill beside Llyn Dinas.