This is the same as the Highland Each Uisge. Yeats, in Irish Fairy and Folk Tales (p.94), tells us that the aughiska were once common and used to come out of the water — particularly, it seems, in November — and gallop along the sands or over the fields, and if people could get them away from the fields and saddle and bridle them, they would make the finest horses. But they must be ridden inland, for if they got so much as a glimpse of salt water they would gallop headlong away, carrying their riders with them, bear them deep into the sea and there devour them. It was said also that the untamed aughiska used to devour mortal cattle.

[Motifs: B184.1.3; F234.1.8; G303.3.3.1.3]