I didn't know anything about the story of this film going in, but it quickly became clear this wasn't just a fun trekking/diving documentary, where the audience is allowed to ogle the scenery. The dive of this Finnish company quickly turns sour (read deadly) and the first half hour is spent recounting this fateful event.
What follows is a bit more surprising. The survivors of the team organize an illegal rescue attempt, after local authorities sealed off the cave with no intentions of getting the bodies out. It's a pretty thrilling setup where the danger is glaringly obvious, further fuelled by the secretive nature of the operation.
The problem is that the footage isn't terribly exciting and no matter how thrilling the subject is, after an hour of very samey diving scenes my interest had waned a little. While I generally prefer documentaries to be as realistic as possible, the tough circumstances this was made were difficult to mask. Some subtle cinematic touch-ups might've helped to better get that across. Definitely worth a watch though.