This is the story of Liban the mermaid, although she didn't start off life as a mermaid. Her sighting in 558 was written about in The Annals of the Kingdom of Ireland, compiled in 1636. It is interesting to see that this mermaid is held in high esteem by the church (even considered holy) despite other stories of pagan mermaids and the belief that mermaids lacked a soul.
In AD 90 a sacred well overflowed forming Lough Neagh. Eochaidh and all his children, excepting his daughter Liban, were drowned. Liban was swept below the lake to a cave where she and her dog lived for twelve months under God's protection. Eventually Liban became bored and lonely and prayed to God that she could become a salmon and join th eother fishes. Her prayer was granted by way of a tail only; her dog was changed into an otter. Liban swam the seas as a mermaid for hundreds of years.
In 557 Beoc, a fisherman and missionary, was sent by St.Comgall to Rome to speak with Pope Gregory. At sea Beoc heard the most beautiful singing below his boat that his crew thought it must be angles. Hearing them, Liban swam to the surface saying:
"I have lived for hundreds of years beneath the sea, and I have come hither to fix a day and a place of meeting with thee. I shall now go westward, and I beseech thee, for the sake of the holy men of Dalraida, to come to Inver Ollarba to meet me, on this same day at the end of a year. Say also to Comgalland to the other holy men of Bangor, all that I say to thee. Come with thy boats and thy fishing nets, and thou shalt take me from the waters in which I have lived."
Beoc finished his journey to Rome and on his return to Ireland told St. Comgall and the rest at the monastary of his meeting with the mermaid.
On the appointed meeting day all the men arrived at Onver Ollarba. They caught Liban, took her ashore and placed her in a boat filled with water where the crowd that had gathered could look at her. After a while the Saints told Liban that she could choose to die and go straight to Heaven or she could live for three hundred years on land and then go to heaven. She chose to go to heaven immediatly, was baptized by St. Comgall and was buried at Beoc's church, Teo-da-Beoc. There she is revered and supposedly miracles have occured through her.