Matt Damon has played action hero Jason Bourne, an astronaut stranded on Mars and dozens of other characters, but it was his role as the Greek King Odysseus that he said presented his biggest on-screen challenge.
Director Christopher Nolan insisted on practical effects and real-world scale over digital shortcuts for his telling of The Odyssey, which will debut in theatres on July 17.
The nearly three-hour movie from Universal Pictures, the first feature film shot entirely with IMAX cameras, adapts one of the oldest surviving stories in human history.
"This is how a movie would have been made 80 years ago," Damon said.
"Everything's in-camera. You know, if you see a thousand people, then there are a thousand people there. The ships, those are real ships in the background."
Nolan's Odyssey was shot in six countries, including Morocco, Greece and Iceland.
Damon and fellow cast members worked through extreme weather conditions with high winds and pounding rain that battered them on ships out in the open ocean.
"It was without question the hardest film, the most challenging, that I've ever done," he said.
The Odyssey, the epic poem, dates back in written form to around the seventh or eighth century BC and is widely believed to have been sung before that in oral tradition.
The story centres on Odysseus as he tries to get home after devising the strategy that won the Greeks the Trojan War.
On his voyage across the seas, Odysseus encounters witches, monsters and gods before finally getting back to his wife, Penelope (Anne Hathaway), and son, Telemachus (Tom Holland).
"What's so cool about the text is how relevant it is, you know, and the lessons that we can all learn from this piece of material," Holland said.
"That is the importance of love and loyalty, perseverance, failure, facing your consequences, understanding right and wrong, and all that sort of stuff. I think that it's super topical."
The movie, Nolan's follow-up to the 2023 blockbuster and best picture winner Oppenheimer, cost $US250 million ($A360 million) to make.
Fans began snapping up Odyssey tickets a year ago when seats at select IMAX theatres were put on sale.
Box office forecasters expect its opening weekend will haul in between $US80 million ($A115 million) and $US100 million ($A144 million) at US and Canadian box offices.
Zendaya, who plays the goddess Athena, said she felt "speechless" after seeing Nolan's take on the classic story.
"It is such a visceral emotional experience and you feel very much that you are on this odyssey with Odysseus the whole time," she said.
"You are with him, you know, from the beginning to the end. It's unrelenting."