From flooded passages lit by headlamps to urgent voices echoing off cramped walls, the director of “The Cave” — the first big-screen retelling of Thai rescue operation — promises to capture the peril of the mission when it premieres at Busan International Film Festival.

“No one is going to say, ‘Oh that looks like a set’,” Thai-Irish filmmaker Tom Waller told AFP ahead of the Saturday debut at Asia’s biggest film festival in South Korea.

“Those who suffer from claustrophobia, there should be a warning… (you) might get a little bit anxious,” he joked.

The 2018 mission to extract 12 young Thai footballers and their coach — known as the “Wild Boars” — from Tham Luang cave in northern Thailand captivated people around the world.

After wandering into the complex during the rainy season, the team were trapped by floodwaters for 18 days before they were sedated, fitted with masks, and dragged to freedom through kilometres (miles) of narrow passageways.

Waller’s challenge: to recreate the conditions of the dank, dark environment that made the rescue of the “Wild Boars” so harrowing and unprecedented.

To do so he filmed in similar caves around Thailand and employed four of the rescue divers to star as themselves.

“We had to deal with snakes, huge spiders,” Waller said.