Analysis of information sources in references of the Wikipedia article "Lough Swilly" in English language version.
In some parts of the country it [súil] is applied to a whirlpool in a river ; and in this sense it has given name to the river Swilly in Donegal, which is called in the Annals, suileach, i. e. abounding in eyes or whirlpools. The river gave name to Lough Swilly
The River Swilly [..] takes its name from Suileach (sharp sighted), a man eating water monster known for its many eyes and immense size
Suileach [..] Multi-eyed, eponymous sea-monster of Lough Swilly (Co. Donegal) thought to have been dispatched by St Colum Cille (521–95)
