Phoebe Dynevor befriended a water hose making her shark movie 'Thrash'

Watching her new shark movie “Thrash” was fun for Phoebe Dynevor. Less so actually making the thing.

In director Tommy Wirkola's “Thrash” (streaming now on Netflix), a coastal South Carolina town is nailed by a Category 5 hurricane, sending its residents scrambling. A nearby levee breaks and a pack of bull sharks comes swimming in via the flood waters, ready to chomp on locals who haven’t left yet.

One of those is Lisa (Dynevor), a very pregnant woman attempting to drive out of town but who gets stuck in her car when it crashes into a tree. Being trapped in her vehicle by a large branch as the water rises around her is a dangerous enough situation. It reaches a fever pitch when fearsome fins are seen nearby.

That scene was the hardest for Dynevor to film – and not because of any fishy menaces. 

“I’ve never been claustrophobic before, but I really did feel it in the car,” says the British “Bridgerton” actress. While filming in Melbourne during the winter, she wore two wetsuits underneath her faux pregnancy belly. But everybody was clad in wetsuits and wading in, from camera guys to her makeup team. “That was kind of cool that we were all experiencing that together.”

While she didn’t feel alone, Dynevor recalls some freakouts when weighted belts were put on top of her, as the seat belt wasn’t holding her down enough and “I would have risen with the water.” That “was pretty terrifying, too. I felt mostly very safe, but there were moments where I definitely had to get out of the car and just take a second.”

As one of the leads alongside Whitney Peak, Dynedvor did "a good job" of keeping "Thrash" as grounded as possible, producer Adam McKay says. "The actor has to keep the stakes high and real. ... With any shark movie, it's always right on the edge of drifting into camp. And that was the No. 1 challenge with a movie like this that's such a heightened scenario."

Dynevor survived filming "Thrash" thanks to a couple of coping mechanisms. For one, she and the hot water hose became good pals. 

“The water itself had to be cold because if it was too hot, then you could see the steam rising,” she explains. To keep warm, a hot hose was passed around and would go “straight into my wetsuit between takes, so that was my best friend during that shoot.”

She also had a go-to routine every night after filming days: Dynevor “would take a really, really long, very, very hot shower,” followed by binge-watching episodes of “The Office” or “something like that where I can just have a giggle when I get home.”