An English lake where the boar Twrch Trwyth made a stand against Arthur and his warriors during the grand hunt. Twrch Trwyth killed many men – including Echel Pierced Thigh and Garwyli fab Gwyddawg – before he fled on to Llwch Tawy.
The lake might be Llyn Llech Owen.
Notes
Llwch is the ancient Welsh for an inlet of water, a lake. It corresponds to the Irish lough, Scotch loch, and the English lake.
Source
Culhwch and Olwen | Late 11th century