The Little Mermaid dwells in an underwater kingdom with her father (the sea king or mer-king), her grandmother, and her five sisters. Her five sisters are each born one year apart. When a mermaid turns 15, she is permitted to swim to the surface to watch the world above, and when the sisters become old enough, each of them visits the upper world every year. As each of them returns, the Little Mermaid listens longingly to their various descriptions of the surface and of human beings.