Wikipedia
Muc-sheilche
The Muc-sheilch(e) is a loch monster reported to live in Loch Maree, and its neighbouring lochs.
A Mr Banks of Letterewe tried at great expense to drain Loch-na-Bèiste near Aultbea, in the 1850s, but failed. He also tried to poison it with quicklime. Loch-na-Bèiste is Scottish Gaelic for "loch of the beast", beast often being used for a loch monster in Ireland especially. The term loosely translates as "turtle-pig".
It has been suggested to be a large eel.