In most parts of the world Merrows fairies appear as Mermaids. However in Ireland, they appear in human form with flatter feet and webbed hands. Merrows love the sea but can live ashore. There are many instances reported of unions between men and Merrows. One of the reasons for this is that Merrows have to shed their cloaks to come ashore. They need these cloaks to return to the sea. Anyone who finds such a cloak has power over the Merrow to whom the cloak belongs.

Some men steal these cloaks and leave Merrows little choice but to marry them. Merrows make good wifes in the sense that they attend to all their duties. However, they are not affectionate and want only to return to the sea. If they find their cloaks, the urge to return to the sea is so strong they walk out on their husbands and children and do so.

Some Merrows are not Merrows at all. They are humans taken by Merrows to raise as their own. If these children ever stand on land they regain their human roots and can not return to the sea. It is also said that sighting a Merrow can bring ill fortune....fishermen who see them immediately return to port. They also have a tendency to attack those who fall asleep on the shore and attempt to drown them. As with other fairies, a crucifix will ward off such attack as will the sound of a church bell.