'Last Breath' is 'Apollo 13' on the bottom of the ocean

Fact-based thriller prizes authenticity over flash.

Finn Cole, Woody Harrelson and Simi Liu star in “Last Breath.” (Focus Features)

“Last Breath” is a thriller where the villain is math. If you’re trapped on the bottom of the ocean floor with 10 minutes of oxygen, and it takes 30 minutes for rescuers to reach you, it doesn’t matter how good or brave or clever you are. The math is seemingly unavoidable.

Alex Parkinson’s movie, based on his documentary of the same name, skews closely to the facts of what happened to commercial diver Chris Lemons (Finn Cole) in the North Sea on one stormy night in 2012. It’s a grounded, edge-of-your-seat drama that, like “Apollo 13,” focuses not on one person’s heroics, but on a large group of smart people working together to try and solve a seemingly unsolvable problem. To beat the math.

The lives of commercial “saturation divers” like Chris are fascinating even when things go right. The divers, who repair oil pipelines that run along the bottom of the sea, live in pressurized capsules – basically giant tin cans – for a month, so they can quickly get into the water and do their work. In the first half-hour, Stevenson revels in the tactile physical details of this world, the camera lingering on gauges and hoses and equipment.

The characterizations of the divers are a little more simple, but still effective. As played by Cole, Chris is an earnest young man who pines for his fiancee Morag (Bobby Rainsbury) back home. He’s only been on a few dives, and the grizzled Duncan (Woody Harrelson) has been his mentor and father figure on every one. But Duncan is on his last dive, pushed out by the company after 20 years, and can’t imagine life outside the tin can. The third member of the team, Dave (Simi Liu), is a by-the-book alpha nicknamed “the Vulcan” by his crewmates.

Using underwater cinematography and attention to detail, “Last Breath” puts you in the capsule with these divers, and effectively uses the darkness and the murkiness of the sea to build suspense. At first, the operation seems to be going smoothly, but a freak combination of equipment failure, bad weather and bad luck ends up leaving Chris stranded at the bottom of the sea with just those few minutes of oxygen.

“Last Breath” painstakingly details the complicated steps needed to rescue him, involving both Duncan and Dave in the submerged diving bell and the crew on the boat up topside. Just when you think one breakthrough is going to lead to Chris’ rescue, another complication arises.

The performances are all strong and understated, especially Harrelson as the veteran determined to recover his protege, and Mark Bonnar as the worried dive supervisor on the bridge of the ship. I was hooked in from the first minute to the last of “Last Breath,” a satisfyingly old-fashioned adventure movie.

“Last Breath” opens Friday in theaters. In Madison, it will play at Marcus Point, Marcus Palace, AMC Fitchburg 18 and Flix Brewhouse Madison.