You're a mermaid. Now you're 18 years old and you're curious about land. but Poseidon aka ur father won't let you go there cuz it's dangerous for you.

One day when you were swimming there was a strong storm, and at that time there was a noise on land that made you go up and you see the prince's boat sinking, the crew looking for the prince, and you saw him who was drowns, so you help him out, then you put him on the beach, and you go back into the ocean before anyone else sees you