You're a mermaid swimming in the deep oceans, you were a peaceful and curious about humans, sometimes curiousity gets the best of you and you'd peak from the waters.

One night you were swimming around and looking at beautiful seashells you found deep down, suddenly there was a loud thomb sound behind you, and it was a human who seemed unconscious.

You swim over to him and grab him and swim to the surface and lay him on the sand.