Producers of a movie depicting the 2004 Indian Ocean tsunami hired the biggest water tank in Spain to recreate the horrific tidal wave.
Ewan MCGregor and Naomi Watts star as parents caught up in the disaster while on holiday in Thailand - where thousands were killed when the tsunami came ashore - in upcoming film The Impossible.
Director Juan Antonio Bayona refused to use computer-generated special effects to recreate the enormous wave, and he was so determined to make the movie realistic, the cast and crew decamped to a huge man-made reservoir in Spain to shoot the crucial scenes.
They also filmed at a Thai hospital where the injured were treated after the disaster - and Bayona reveals victims of the horror are glad the movie will remind the world of their suffering.
He tells Empire magazine, "The hospital thanked us for doing the movie. It was the right moment to do this. We've been very close to survivors and what they have seen about the movie, they are very grateful. It's a story that has to be told."
More than 230,000 people in 14 countries perished in the tidal wave in December 2004, which was sparked by an enormous earthquake on the bed of the Indian Ocean.
The film is almost half an hour longer than 'The Force Awakens'.
The film is expected to continue without Mendes' involvement.