Finnish Folk Tales:
The Mermaid of Laane

Many Finnish folk tales feature mermaids, water sprites, and aquatic goddesses. The mermaid in the following story appears as a young girl without a fish's tail. People knew she was a mermaid by her beautiful voice, golden comb and ability to change form - plus the fact that she lived in the sea!

One day the mermaid took a mortal lover to her land beneath the sea. There he discovered that she was a great queen and he her royal consort. He had all the riches that anyone could ask, but he had to promise the mermaid one thing. Once a week she would fast, and on that day he could not see her. He agreed, of course, but over time he began to grow nervous about her weekly disappearings. He suspected that she had a lover. Despite her assurances he could not give up his distrust. He learned that on her fast days she retired to a single room in the castle where she remained in all day. The room had thick curtains at the windows so no one could see inside.

After several months, the man found a small opening in the curtains and he was finally able to see the inside of the mysterious room. It was not really a room at all but more like a large tank, full of water. His wife he saw floating in it, normal from the waist up, but from there down she was a fish. Horrified, he ran from the window. I don't know why he was so frightened, surely this sort of thing is pretty common in Finnish folk tales. The next day the mermaid told him that he must leave because he had broken his promise. The man was returned to the surface world. There he discovered that many, many years had passed. No one on the surface knew him, and more he was now a very old man. A sort time later his body was found floating in the sea.

This is a common type of folk tale, see the story of Melusina for a comparison. The mermaid's secret ultimately is not important, what is violated is trust. When you cannot trust you cannot be trusted, as they know even in Finnish folk tales.