Colin Farrell says he developed panic attacks while filming intense scenes for his new film, Thirteen Lives.
The movie, directed by Ron Howard, tells the story of the real-life rescue of 12 young football players and their coach from the flooded Tham Luang cave in Thailand four years ago.
Farrell, who plays rescue diver John Volanthen, told Entertainment Tonight filming the underwater scenes was "terrifying".
"It was scary. I'm not a great swimmer anyway, not that we were swimming, not that we were treading water - we had to stay on the surface - but they built a really impressive network of caves," he said.
"It was about four or five different caves that were based on the topography of the caves, the Tham Luang caves in Thailand, and they filled them full of water, and we'd go down and there was no up."