Mandy Moore and Claire Holt acted underwater for 90% of the movie for 47 METERS DOWN, and it wasn't easy. The actresses spent 6 to 7 hours under water for weeks during the production. Not only did they have to act 20 feet below the water surface, but they had to be conscious of their breathing techniques. Like in the movie, they could experience serious health issues if they weren't careful. The heroines of 47 METER DOWN explain their experience to CineMovie and why they had to yell "cut" to the man swimming around in a plastic shark head.