The legendary woman, Scál Ní Mhuirnain, has given her name to Annascaul Lake, Annascaul River and ultimately to the village of Annascaul
The legend features Cú Chulainn, the legendary Irish hero and protagonist of the Táin Bó Cualinge.
It is said that Cú Chulainn tried to rescue Scál from an ugly giant. The fight between Cú Chulainn and the giant took place from the cliffs on either side of the lake. The two fought for days by throwing boulders at each other: many of the standing stones that can be found in the Annascaul area are supposed to be remnants of the contest.
After about a week Cú Chulainn weakened enough to be hit by a rock and gave a mighty groan. Scál heard the cry and assumed he was killed and threw herself into the lake, drowning herself. The battle continued for another day with Cú Chulainn eventually being the victor. On top of nearby Dromavally Hill are three stone cairns known as the bed, house, and grave of Cú Chulainn.