Solo-movie role in The Shallows was sink or swim for Lively

Blake Lively plays a surfer menaced by a shark in The Shallows. Vince Valitutti / CTMG

There’s something electrifying about watching an actor carry a movie single-handedly.

Think Tom Hanks in Cast Away, Matt Damon in The Martian, Sandra Bullock in Gravity or Robert Redford in All Is Lost – all of them delivered some of their finest work in these survival stories, for which they were alone on screen for most of the film.

It is no surprise, then, that Blake Lively was drawn to The Shallows, the visceral tale of a surfer who gets trapped 200 yards from shore on a rocky outcrop, with one of man's oldest predators – a great white shark – circling her. So begins her battle to survive and reach the safety that is so agonisingly close yet seemingly impossible to reach.

“Carrying an entire film is challenging,” says the 28-year-old Los Angeles native, who spends about 90 per cent alone on screen. “I had no co-star. And I really rely on my co-stars and my directors – I need them. It’s like dancing alone. You really need them and the choreography.”

There wasn’t even a shark for her to bounce off. “There was a blue curtain,” she says, referring to the special-effects prop that allowed the creature to be added digitally later on.

Fortunately, Lively could turn to her husband, Deadpool star Ryan Reynolds, for support and expert advice on working on a solo movie. His performance in the indie movie Buried – in which he plays a lorry driver who wakes up to find himself in a coffin, buried alive – was one of the reasons she wanted to make The Shallows, she says.

Buried is a true “solo” movie – although Reynolds’s character has a mobile phone with which he can communicate with the outside world, the camera never moves outside the coffin – and Lively marvels at how her husband survived such a claustrophobic shoot. As a result, his experience was ­invaluable to her.

“One of the best pieces of advice he gave was that ‘this is as hard for the crew as it is for you’,” she says. “Everybody’s energy is focused on one thing in every moment. And it’s physically and emotionally demanding ... it is an athletic event for everyone. You feel so bonded. You all feel like you’ve survived something at the end.”

While location filming took place on the “beautiful” Lord Howe Island in Australia (standing in for a beach in Mexico), Lively also spent a lot of time in a water tank.

“I didn’t have a stunt double for the last two weeks, having to scream, cry, fight for my life in four-foot waves – going ­underwater, coming above water,” she says. “So you’re fighting the elements and you’re using your imagination and you hope that the director’s imagination then lines up with yours.”

Lively was in good hands – Spanish director Jaume Collet-Serra (who made Unknown, Non Stop and Run All Night, all of which star Liam Neeson). The film opened in the United States in June to decent reviews and has already grossed $70 million (Dh257.1m) worldwide – four times its ­modest budget.

It marks another high-point in Lively's burgeoning career. As well as starring in six seasons of TV teen drama Gossip Girl, on the big screen she has worked with Oliver Stone (­Savages), Ben Affleck (The Town) and Woody ­Allen (Café Society).

She says doesn’t take such ­successes for granted.

“Anytime I get hired, I pop open my hot chocolate,” she says, ­currently pregnant with her second child with Reynolds.

“Knowing that I have this fun summer thriller coming out that also has an emotional gravity to it … you really feel all that joy, ­excitement and pride.”

And perhaps just a touch of sea-sickness.

• The Shallows is in cinemas from today