In new horror Underwater, mysterious creatures terrorise crew members from a subterranean research station. Star Kristen Stewart discusses the challenging role, plus her reaction to recent project Charlie's Angels flopping at the box office.

Kristen Stewart felt "very claustrophobic" on set for her latest film.

Which is unsurprising, considering it is a horror called Underwater and follows a crew forced to evacuate their mining rig located seven miles beneath the ocean's surface.

Stewart, 29, plays gifted engineer Norah Price who, in the aftermath of a devastating earthquake, manages to save herself and stave off imminent disaster.

Unable to send a distress call to people on land, which is 5,000 miles away, she and the few other survivors face a harrowing march across the bottom of the sea to get help.

Not only that but it turns out mysterious creatures exist alongside them in the murky depths.

"Staring into the utter unknown darkness, whether it's the idea of your life ending or the idea of looking into the ocean, it's just undeniably scary," says LA-born Stewart, who rose to fame as the lead in The Twilight Saga, a series of romance fantasy films based on the books by Stephenie Meyer.

"That's the stuff of nightmares, being stuck in a place where you don't know what's coming at you. That's just kinda like being alive, you know?"

Underwater was filmed in 2017, with Stewart shaving her head for the role.

"It was a nice excuse to do it," she says, when asked what it was like to have such a dramatic hairstyle change.

"I don't know that I'd ever necessarily commit to shaving my head if it wasn't for a movie."

She notes her character, Norah, is someone who is "stripped a little bare".

"I play someone who, in the beginning, is a little bit uncaring of herself," she says.

"She seems like somebody who is very spartan and gets in and out of a suit six or seven times a day as a mechanical oil engineer."

The suits in question, designed for all the crew members on the rig, weighed between 65lb and 100lb (29kg-45kg) and could withstand being submerged in water and strung up from the ceiling.

Backpack-style supports were built into the interior of the suits to help the cast manage the weight, while shoulder pads, straps and harnesses were placed to distributed the weight more evenly as they moved about.

But Stewart admits it was "awful" filming at times, as she felt "super stifled".

"Quite often we were in water and when we weren't in water, we were trudging through sand, and walking in sand is just difficult to do - imagine in a 100lb suit," she says.

Chuckling softly, Stewart adds: "And then they're like, 'Run, something's coming after you'. You're like, 'I can't run'. It was uncomfortable, for sure. But that was the goal."

Award-winning actress Stewart has had an interesting career. Since the hugely successful Twilight franchise - in which she played a teenager who falls in love with a vampire - ended in 2012, she has chosen more indie projects, and has certainly proven her credibility.

Notable roles include Clouds of Sils Maria by French film director, screenwriter and film critic Olivier Assayas, for which she became the first American to win France's prestigious Caesar Award - their equivalent of an Oscar.

She later worked with Assayas again for supernatural psychological thriller Personal Shopper.

There was also coming-of-age comedy-drama Adventureland, with Jesse Eisenberg, and the devastatingly sad Still Alice, in which she plays the youngest daughter of a woman who gets diagnosed with Alzheimer's disease, played by Julianne Moore.

At the end of last year, she made a return to mainstream cinema as Sabina Wilson in the Charlie's Angels reboot, which was written and directed by Elizabeth Banks.

Unfortunately, the film ended up being a box office flop. Then there is the matter of the film critic's reviews which, it is fair to say, have been mixed.

Asked if she will look at the commercial performance of Underwater differently, coming off the back of her experience with Charlie's Angels, a usually forthright Stewart hesitates at first, trying to find the right words.

"I am really proud of Charlie's Angels. I like the movie. I like watching it. I'm glad that it exists in the world," she says.

"I'm glad that not as many people saw a good movie versus a tonne of people seeing something that I thought was bad and it wasn't worth it. So, for that, I genuinely am thankful.

"Also, I think it's a weird time to release movies about women right now, blah blah. Not to get into it, whatever, but it's a tough thing to promote."

The star seems on a roll now, opening up sincerely about the success of her work in general.

"And then, whether or not Underwater does well ... I never really think my movies are going to do that well," she says.

"It's always a surprise. The only thing I've ever done that was very successful was Twilight and that was such a shock. I've always been in the realm of small indie movies.

"I think, when things are done with good intentions, there's a group of people - big or small - for every impulse, artistically.

"I hope Underwater does well, genuinely I am pretty proud of it. It's pretty good, it's scary, and it's worth it.

"I don't know, I've seen a lot of worse movies do better."

Underwater is in cinemas on January 23.