The King Kong star appears opposite Ewan McGregor in the new disaster epic, which tells the story of real-life survivor Maria Belon as she struggles to find her family in Thailand in the aftermath of the 2004 Indian Ocean tsunami.
Watts filmed a number of underwater scenes for the movie, and director Juan Antonio Bayona has revealed the shoot made his star sick.
He tells the New York Daily News, "It was very demanding physically. From the first day, Naomi had bronchitis and stomach problems because she was swallowing a lot of water. But no matter how exhausted or emotionally drained she was, I could always ask for another take - and she loved that."
The hard work appears to have paid off for Watts - she has received Best Actress nominations for the upcoming Golden Globes and Screen Actors Guild Awards, and she is tipped to land an Oscars nod when the Academy Awards shortlist is announced on 10 January (13).