If you write the script for a movie about street racers, the characters have to break the speed limit to create drama. If you want to make a movie about mountain climbing, wreck diving, cave diving or treasure hunting, you need to have some license to create drama.
No one is going to watch a diver dig through the dish room on the Doria for ten minutes and the do two hours of deco on a hang bar. It's realistic, but dull as dirt. A fictionalized Cave name will work just as well a real one, since there're probably a thousand miles of caves that are unexplored in Florida alone.
Th big problem for making this movie will be logistical, since everyone involve will need adiquate certification and of course, insurance. Then, of course, a good, safe stand-in cave will be needed for filming. The cost of filming underwater is probably the primary reason so few movies about diving get made. A couple days of bad weather will disrupt filming for weeks. I assume a cave would offer some pretty tough challenges, too. I hope they have some luck and make a great movie. Hopefully, they can find the right story and the right people to give tech advise.