Llyn Dinas Llyn Dinas is a beautiful and mysterious lake in the Snowdonia mountains of North Wales. It takes its name from the nearby Dinas Emrys the ancient site of Vortigerns refuge. The surface of Llyn Dinas reflects the Dinas Emrys rocky hillocock which looms over it. Legend tells that Llyn Dinas was the site of a battle between Sir Owein, one of Arthur's knights, and a giant. Vortigern is also said to have concealed the throne of Britain under a massive stone in this area. Legend also tells that Merlin's treasure is buried under a hill besides the beautiful lake.