To see a mermaid in your dream, signifies the female aspect of yourself that is mysterious and secretive. It may also show a fear of sex. In particular, for a man to dream of a mermaid, it indicates that he is having fears of being drowned by the feminine aspect of his psyche. For a woman, it suggests doubts over her femininity.
Well, a lot of people say that the sea represents the unconscious. Of course this may or may not be true in your personal symbolism. Maybe the sea has other meanings for you. But the mermaid is an interesting symbol because it lives in the sea but is human, and because it is part human part fish, and because of its folk relationship with actual humans. I am sure there are other things. I don't know about the idea of 'being drowned by the feminine' and whatnot... even if you decide the mermaid does symbolize a feminine aspect of yourself, the message would depend on the situation/actions in the dream. For example, it would seem to indicate being 'drowned' by the feminine part of yourself if the mermaid had grabbed onto you and was trying to drown you.
