Prior to filming, Kate Winslet had discussed her role with close friend Leonardo DiCaprio. Leo, who had finished filming The Revenant (2015) in equally-gruelling conditions, warned her of how bitterly cold the temperature would be and how difficult filming would become. Once filming had commenced, Kate would send texts to Leo of her covered in snow and hanging off the mountain, with the caption: "this one's for you, honey!"
Originally, only Kate Winslet's stunt double was going to plunge into the freezing water, as the studio was worried about Kate's safety. Kate, however, was adamant that she should do it, and demanded the director to allow her. "I'm the water and ice person! Water's my thing!", Kate recounted, referring to the extensive shoot of filming whilst submerged in water for months on end for Titanic.
After Michael Fassbender and Margot Robbie dropped out of the project, they were replaced by Charlie Hunnam and Rosamund Pike. However, both dropped out of the project after it was put into turnaround. Idris Elba and Kate Winslet were eventually cast.
It was during this 2017 shoot on location in Vancouver that Idris Elba first met wife-to-be Sabrina Dhowre Elba at a party.