It's based on a movie, The Abyss! > v <

Freddy Robbins and Bonnie Harmon are formerly married petroleum engineers who still have some issues to work out. They are drafted to assist a gung-ho Navy SEAL with a top-secret recovery operation: a nuclear sub has been ambushed and sank, under mysterious circumstances, in some of the deepest waters on Earth.

Also, I really like this song. It reminds me of the idea very much.

FNAF x The Abyss OST - Don't Give Up

https://youtu.be/_KSEo0vu1UE