An entry in the Open Water cycle of menaced-on-holiday movies, 47 Meters Down (aka In the Deep) even goes back to the source and pits a pair of luckless, perhaps foolish tourists against the big threats of open water – sharks and the sea. In Open Water, a doomed couple bobbed about on the surface of an ocean, unable to see what was coming for them … the variation here is that their ordeal (and the bulk of the film) takes place entirely underwater – and co-writer/director Johannes Roberts ups the suspense by sticking to their POV so there are no cutaways to would-be rescuers worrying up on the boat.
Lisa (Mandy Moore), depressed after the break-up of a long-term relationship, takes a Mexican holiday with her more impulsive sister Kate (Claire Holt) to cheer herself up … and a couple of guys they meet in a bar (Yani Gellman, Chris J. Johnson) convince them to take a cut-price shark-spotting trip out in a small boat captained by competent-seeming Taylor (Matthew Modine). Lowered into the sea in a cage, the sisters are supposed to go no deeper than five meters but the winch breaks and the cage plunges to the bottom – with a heavy chunk of equipment on the top hatch to keep them trapped, unless one of them takes off the helmet of their scuba gear to slip between the bars.
As in Open Water, Adrift (released in some territories as Open Water 2), Black Water, Frozen (the ski-lift one not the Disney), 247°F and others of this cycle, the film plays out mostly in real time as Lisa and Kate deal with the minutiae of their quandary – having to swim up from the safety of the cage to shark-infested waters to get a signal to communicate with Taylor, a strictly limited air supply and (when replacement tanks are supplied) the possibility they’ll hallucinate from excess nitrogen (which cues a tricksy raptures of the deep stretch in the third act), the threat of the bends if they just panic and break for the surface, rescue attempts which just make their situation worse and frequent swim-bys from the gathering sharks as minor cuts leak blood into the water.
Moore and Holt are good, playing most of the film behind masks, are engaging enough without overdoing the backstory, and the all-CGI sharks are far better realised than the fish in SyFY schlock like the Sharknado or 2-Headed Shark Attack films. Co-written by Roberts’ usual collaborator Ernest Riera.