The creature effects were done practically.
The water tank was a set built for this film.
Scott Walker got the idea for the story after spending time at a beach house built on top of a water tank.
The creature suit was designed to only be worn by 45kg performer, Regina Hegelmann. The suit weighed approximately 36kgs / 80lbs and when on, she had only 2% of her vision. Many of the attack scenes required her to fight underwater in near darkness and hold her breath for up to 4 minutes.
NOTE: there are a very few people who can actually hold their breath that long.
NOTE: there are a very few people who can actually hold their breath that long.
One day into pre-production, New Zealand entered its longest lockdown of the pandemic and production was shut down for 5 months.