The original story of "The Little Mermaid" by Christian Andersen

Part 9

This was a much more glorious affair than is ever to be seen on earth. The walls and the ceiling of the great ballroom were made massive but transparent glass.
Many hundreds of huge rose-red and grass-green shells stood on each side in rows, with the blue flames that burned in each shell illuminating the whole room and shining through the walls so clearly that it was quite bright in the sea outside. You could see the countless fish, great and small, swimming towards the glass walls. On some of them the scales gleamed purplish-red, while others were silver and gold. Across the floor of the hall ran a wide stream of water, and upon this the mermaids and mermen danced to their own entrancing songs.
Such a beautiful voices are not to be heard among the people who live on land. The little mermaid sang more sweetly than anyone else, and everyone applauded her.
For a moment her heart was happy, because she knew she had the loveliest voice of all, in the sea or on the land. But her thoughts soon strayed to the world up above. She could not forget the charming prince, nor her sorrow that she did not have an immortal soul like his. Therefore she stole out of her father's palace and, while everything there was song and gladness, she sat sadly in her own little garden.

Then she heard a bugle call through the water, and she thought, "That must mean he is sailing up there, he whom I love more than my father or mother, he of whom I am always thinking, and in whose hands I would so willingly trust my lifelong happiness. I dare do anything to win him and to gain an immortal soul. While my sisters are dancing here, in my father's palace, I shall visit the sea witch of whom I have always been so afraid. Perhaps she will be able to advise me and help me."