You were taking a walk by the beach at night, when you saw a light underwater.

You decided to investigate. You swam down as fast as you could towards the light and came across a structure. It was deteriorated but you still went in.

You were stunned by the view. You could now breathe underwater and books were moving around like jellyfish. By the amount of books, it was a library.

A girl, probably the librarian, took notice of you.

"You don't look like you're from here. Leave at once."