Let's give credit where credit is due, the film has some gorgeous cinematography and the concept was awesome. Underwater sets are not easy to achieve, so the set designers get an A+. Truly, it was a beautiful yet terrifying thing to look at.
Now let's get to the bad.
Firstly, what a waste of potential. This concept was FANTASTIC- and then they ruined it with overused movie tropes and terrible casting. The two main characters have zero chemistry and the whole Pierre plotline is something I've seen in hundreds of different horror films. Not great.
Secondly, the only dialogue that made much sense was the french dialogue. I don't know who is more at fault, the writers or the cast that was incapable of making this believable.
The ending was so stupid.
Listen, don't waste your time if you're looking for something that is anything other than interesting to look at. Truly, the cinematographers and designers deserved a better cast and writers to work with.