A Disney Depiction

Ariel (she actually has a name this time), is a sixteen year old mermaid, unhappy with her life under the sea. She is curious about the human world and, with the help of her friend Flounder, a fish, she collects artifacts from the world above. Knowing full well that any contact between merpeople and humans is strictly forbidden, she travels to the surface to watch the birthday celebration for Prince Eric. Ariel, upon seeing the prince, falls madly in love with him; and when a terrible storm hits, she rescues him and returns him to the shore unconscious. She sings to him, but when he begins to stir, she dives back under the water, leaving him with only a vaque impression of the girl with the beautiful voice who saved him. He vows to find her, just as she vows to find a way to join him on land.
(Spoilers Ahead)

When Ariel's father, King Triton, learns of his daughter's adventure, he destroyes all of her human treasures, forbidding her from ever visiting the surface again. Out of anger and desparation, Ariel invokes the help of the evil sea witch, Ursula. Ursula promises to give Ariel legs, but at the cost of her voice, which Ursula captures in a shell she wears around her neck. She also must kiss the prince within three days or she will transform back into a mermaid and belong to Ursula. Ariel recieves her legs and is helped to the surface by her sea friends, no cutting her tail in half, no walking on knives.

On, the shore, she is found by Prince Eric, who at first thinks she is the girl who saved him, but discards that idea when he finds out she cannot speak. He helps her to the palace where the servants decide that she must be a shipwreck survivor. After a few "almost kisses," Ursula becomes worried that Ariel may succeed, so she transforms her self into a human, Vanessa, and gives herself Ariel's voice. Upon hearing Vanessa's "voice" Prince Eric falls into a trance and says that he and Vanessa are to be married the next day.

When Scuttle, the bird, descovers that Vanessa is really Ursula, he hurries to tell Ariel and they both rush off to stop the wedding. When the shell holding Ariel's voice is broken, her voice is returned and Prince Eric is released from his trance. Realising that Ariel is indeed the girl who saved him, he rushes to kiss her, but the sun sets first and Ariel turns back into a mermaid and is captured by Ursula and taken back to her lair. Here, King Triton sacrafices himself for his daughter and Ursula declares herself Queen of the Oceans. Prince Eric and Ariel both fight against Ursula and when she is defeated, all of the spells are lifted and King Triton is freed. Seeing how much Ariel truly loves Eric, he transforms her back into a human so that she might stay with him.