James Gray’s “The Lost City of Z” was partially filmed in the rainforests of South America, meaning the stars of the period drama faced a treacherous environment not unlike that of their characters.

“It was the whole experience that was extreme,” Tom Holland said in an interview with TheWrap’s Stuart Brazell. “It wasn’t just one thing, it was everything. We were really in the thick of it, we were thrown in at the deep end … The jungle is relentless, there’s no breaks.”

Charlie Hunnam stars in the film, written and directed by Gray, as Percy Fawcett, the real-life early 20th Century British explorer who made several trips to the Amazon in search of a lost city, only to eventually disappear himself.

Also Read: 'The Lost City of Z' Review: Charlie Hunnam Explores the Amazon in Stirring Saga

The crew journeyed to Colombia for part of the shoot, leading to one particularly harrowing run-in with mother nature.

“The desire to experience grand adventure I think infected all of us during this,” Hunnam said. “That sense of exploration. We ended up going, as the film went on, further and further and further into the jungle.”

Eventually they wound up two hours up the river into the jungle, caught in the middle of a massive storm. “The type of storm that you can’t really imagine unless you’ve been in the rainforest. Violent rain coupled with incredibly violent lightning crashing all around us,” he said.

But despite the danger, Hunnam wanted to stay and keep shooting, arguing with the producers and the director that the nasty conditions were precisely the reason they came to the rainforest in the first place.

Also Read: Charlie Hunnam Says He Was Almost Struck By Lightning While Making 'Lost City of Z'

“A bolt of lightning hit a tree about 20 feet from me, and the tree exploded,” he said. “What was left of it was set on fire. The shockwave, the energy that then transferred into the ground, knocked me off my feet. Which was a pretty extraordinary interaction with the power of the natural world.”

“It was definitely worth our while, but it was 100 percent worth our while to make an authentic movie,” Holland said. And an authentic movie is what they got, all it took was almost dying.

Sienna Miller also stars in the movie alongside Holland, Hunnam and Robert Pattinson, and she hopes the film reminds moviegoers of the classic Hollywood productions of the 1970s.

Also Read: 'Lost City of Z' Teaser Trailer: Charlie Hunnam, Tom Holland Rumble in the Jungle (Video)

“I hope that they appreciate that this is a proper film. I don’t know that people make films like that anymore,” she said. “If you love cinema, and you understand cinema, you should sit back and absorb this piece of work that James Gray made.”

“It’s sort of a return to classic epic filmmaking,” Hunnam said. “With a very, hopefully, heartfelt and deep, human journey at the center of it.”

25 Summer Movies We're Dying to See, From 'Alien: Covenant' to 'Spider-Man: Homecoming' (Photos)

Summer 2017 is bringing a wealth of promising movies to the cineplez. Here are some of the buzziest.
May 5: "Guardians of the Galaxy Vol. 2"

Chris Pratt, Dave Bautista, Bradley Cooper, and scene-stealer Baby Groot pick up right where they left off in this sequel to the 2014 Marvel hit.
Disney
May 12: "Snatched"

CinemaCon attendees got to see some extended footage of the comedy starring Goldie Hawn and Amy Schumer, who play mother and daughter who go on a vacation together and get involved in some unexpected criminal activity. It looks hilarious, and the movie marks Hawn's return to the big screen after a 15-year absence.
Fox
May 19: "Alien: Covenant"

Fans of the "Alien" franchise have been looking forward to the new film, which welcomes back Michael Fassbender as both Walter/David, as well as new cast members Danny McBride, Katherine Waterston, James Franco and Demian Bichir.
Fox
May 19: "Everything, Everything"

Based on a best-selling YA novel, director Stella Meghie's "Everything, Everything" follows a girl (Amandla Stenberg) who has lived in solitude her entire life because she's allergic to everything, but takes an interest in the boy (Nick Robinson) who's moved in next door.
WB/MGM
May 26: "Baywatch"

Dwayne Johnson, Zac Efron, Alexandra Daddario, Kelly Rohrbach and Priyanka Chopra star in this comedic feature film take on the iconic TV series. The trailers we've seen so far just make fun of Efron's character, and the whole movie looks like eye candy for men and women alike.
Paramount
June 2: "Wonder Woman"

It only took 75 years, but after making a huge splash in last year's "Batman v Superman," DC Comics Amazonian Superheroine finally headlines her own movie this summer. The film stars Gal Gadot and is directed by Patty Jenkins.
Warner Bros.
June 9: "The Mummy"

Tom Cruise headlines this updated take on the classic Universal monster. The remake tells us the story of an ancient princess (Sofia Boutella) who was denied her chance to be the next Pharaoh and wreaks havoc centuries after the fact.
Universal
June 16: "All Eyez On Me"

The Tupac Shakur biopic has excited fans since the announcement of the project, and further casting notices including that of Kat Graham and Danai Gurira have enticed fans further to look forward to its release.
Lionsgate
June 16: "Rough Night"

The first trailer for the film previously titled "Rock That Body" was full of sex, drugs and, yes, murder. It's no wonder that we're so eager to see the comedy starring Scarlett Johansson, Kate McKinnon and Zoe Kravitz.

Sony
June 23: "Transformers: The Last Knight"

Michael Bay returns for his final "Transformers" movie and intends to go out with quite a bang -- literally. Mark Wahlberg also returns and Anthony Hopkins star in the latest installment which sees humanity at war with the Transformers while Optimus Prime is MIA.
Paramount
June 23: "The Big Sick"

Kumail Nanjiani's "The Big Sick" was one of the hottest titles at the Sundance Film Festival and is based on the true story of his relationship with his now-wife, co-screenwriter Emily Gordon (played on screen by Zoe Kazan). When she gets sick with a mysterious illness, he must team up with her parents to overcome the crisis.

Amazon
June 23: "The Beguiled"

Sofia Coppola's drama follows a girls' school in Virginia which takes in a wounded soldier. Soon, sexual tension and jealousy takes over the school. The period drama stars Nicole Kidman, Kirsten Dunst, Elle Fanning and Colin Farrell.
Focus
June 28: "Baby Driver"

From director Edgar Wright, the film revolves around a young but talented getaway driver named Baby, played by Ansel Elgort. In a sign of confidence, Sony's TriStar moved up the release from the dead of August.
Sony
June 30: "Despicable Me 3"

Steve Carell plays not one but two characters in this movie -- Gru and his twin brother, Dru. And the duo team up for one last heist with the assistance, of course, of dozens of minions.
Universal
July 7: "Spider-Man: Homecoming"

After being introduced as part of the Marvel Cinematic Universe last year in "Captain America: Civil War," Tom Holland returns as the web crawler in his standalone film to face off against Michael Keaton's villainous Vulture. Robert Downey Jr. co-stars as Iron Man.

Sony
July 7: "A Ghost Story"

Hot off his Oscar win for "Manchester by the Sea," Casey Affleck stars in "A Ghost Story" alongside talented actress Rooney Mara, the film follows Affleck’s white-sheeted ghost who unstuck in time, forced to watch passively as the woman he loves slowly slip away.
A24
July 7: "Step"

Buzzy Sundance doc "Step" follows a girls’ senior-year high school step team in inner-city Baltimore as they strive to become the first in their families to go to college.
Fox Searchlight
July 14: "War for the Planet of the Apes"

Director Matt Reeves returns for the third movie in the rebooted franchise after helming 2014's "Dawn of the Planet of the Apes." This time, Woody Harrelson is the film's main antagonist, which combined with the franchise's epic CGI apes, should make for a solid sci-fi film.
Fox
July 21: "Dunkirk"

CinemaCon attendees also saw footage of Christopher Nolan's WWII epic, which stars Tom Hardy, Cillian Murphy and Harry Styles as well as newcomer Fionn Whitehead in the lead role. Nolan fans and Styles fans are sure to flock to the theaters.
Warner Bros.
July 21: "Girls Trip"

Jada Pinkett Smith and Queen Latifah reunite 20 years after "Set It Off" along with Regina Hall. The ladies go on a girls trip to New Orleans, which obviously turns wild.
Universal
July 28: "Atomic Blonde"

Charlize Theron's bisexual spy thriller follows MI6’s most lethal assassin through a ticking time bomb of a city simmering with revolution and double-crossing hives of traitors. Theron's Agent Lorraine Broughton is equal parts spycraft, sensuality and savagery.
Focus
August 4: "Detroit"

Director Kathryn Bigelow and producing partner Mark Boal's highly anticipated followup to their acclaimed 2012 drama “Zero Dark Thirty" is another fact-based drama with a stellar cast: John Boyega, Will Poulter, Jason Mitchell, Anthony Mackie and Jack Reynor. The film recounts the racially charged riots that rocked the Motor City in 1967.
August 4: "The Dark Tower"

Fans of Stephen King's genre-defying multi-book saga have been clamoring for a filmed version for decades and the first installment finally arrives with Idris Elba as the Gunslinger Roland Deschain chasing Matthew McConaughey's Man in Black across a highly stylized, scorched-earth landscape.
Sony
August 11: "Annabelle: Creation"

The followup to 2014's supernatural horror thriller "Annabelle" follows a couple who just lost their daughter -- but as soon as they invite a nun and some orphans into their home, some unexplained things begin to happen.
New Line
August 18: "The Hitman's Bodyguard"

Ryan Reynolds and Samuel L. Jackson make a great duo in this action comedy. And Salma Hayek adds another layer of laughs to the movie, which follows a bodyguard (Reynolds) who must get one of the biggest hitman's in the world to The Hague. Obviously, the two have history.
Getty Images