Michael Fassbender and Alicia Vikander are lost at sea

Shooting “The Light Between Oceans” on Cape Campbell, a remote island off the coast of New Zealand, was no walk in the park for stars Alicia Vikander and Michael Fassbender.

In addition to the physical challenges of making a movie in the middle of nowhere, the screenplay also called for the actors to dig deep for a handful of emotionally wrenching scenes.

So, how did the pair cope with all of the pressure?

“We had BB guns and played a lot of music,” says Vikander, 27. “We fished and ate barbecue.”

“Yes, barbecued a lot ,” adds Fassbender, 39.

Vikander and Fassbender also, apparently, fell in love. While the actors have never officially confirmed or denied their romance, they appear to be a couple.

The evidence? They smooched seconds after she won the Best Supporting Actress Oscar for her turn in “The Danish Girl.” She also visited him earlier this year in Australia while he was shooting Ridley Scott’s “Alien: Covenant” in Sydney. While the actors refuse to speak about their personal lives, they make no secret of their admiration for each other.

In fact, says Vikander, one of the reasons she signed on for “The Light Between Oceans” was to toil alongside Fassbender.

“I loved working with Michael,” says Vikander, a native of Gottenberg, Sweden. “I was a huge fan of his. I think he’s proven himself as one of the most diverse and brave actors around.

“I remember so well when I saw him in ‘Hunger’ and ‘Fish Tank’ back home at my favorite cinema in Sweden many years ago … I would love to work with him again.”

Fassbender too admits he was drawn to his co-star long before he actually met her.

“I said to [director] Derek Cianfrance early on, ‘This girl frightens me,’” recalls the actor who was born in Heidelberg, Germany, to a German father and Irish mother. “Alicia is so fierce and brave as a performer. It kind of bowled me over.

“It was great because we had great chemistry from the beginning. We really relied on one another and pushed one another and supported one another, and that’s really the ideal scenario when you’re working together.

“Then, we had fun as well. Between takes we would have a laugh. I always think, for all of us who spend so much time working, it might as well be fun while you’re doing it.”

In the movie, which was produced by Pottstown’s Jeffrey Clifford, Fassbender and Vikander play a lighthouse keeper and his wife who lose their beloved baby not long after she’s born. Around the same time, they find a youngster floating at sea in a rowboat, rescue her, and raise her as their own.

But years later, when they ecounter the child’s real mother (Rachel Weisz) and she explains how she lost her daughter and husband at sea, they are faced with a horrible moral dilemma. Do they tell the truth about the child’s identity or continue living a lie? The movie opens Sept. 2.

“I feel like I’ve been given a gift from Derek to play Isabel,” says Vikander. “He told me she’s a fighter, and she is. She’s a survivor, too, and she’s a girl with her heart on her [sleeve].

“I loved that she was so transparent. … I felt like I didn’t really know where she was heading each day because she does things and says things without thinking, which is quite liberating.

“These characters are good people who sometimes maybe don’t make the most right moral decisions or choices but Isabel acts from the heart always.

“That’s why I don’t think you could really blame her. I loved the challenge of [playing] a woman who, once you got to the heart of her, [you begin] to understand her and her actions.”

For his part, Fassbender says it was easy to be swept up in the psychological intracacies of the tale.

“When I read the script, I was just so moved by the story, first and foremost,” he recalls. “I just thought, ‘Wow, here’s such a rare, and, in a way, old-fashioned human story about ordinary people trying to navigate life.’ I really liked that there wasn’t a clear villain and good guy.

“It just really touched me emotionally and, somewhere primal, it really got to me. … I really find Tom to be a hero. He’s somebody that I would aspire to be like.

“Why? Because he lives by his choices . ... And I think he’s a very noble character. When they first discover the child, he knows in his heart of hearts that the best thing to do is notify the authorities. … He’s a very straight shooter. What you see is what you get.”

Vikander and Fassbender seem to share a similar work ethic. Even before they shot “The Light Between Oceans ” together, they conducted their fast-rising careers very similarly.

Both actors alternate work in big-budget franchises with smaller, more intense films.

Vikander, for instance, recently starred in the highly commercial “Jason Bourne” alongside Matt Damon and is starring as Lara Croft in a reboot of the “Tomb Raider” franchise.

The actress has also lent her presence to a trio of forthcoming dramas, including Wim Wenders’ “Submergence,” Lisa Langseth’s “Euphoria” and the long-delayed “Tulip Fever” with Judi Dench.

“The ‘Bourne’ franchise was such a huge one but I’m a big fan of it, and I got to work with Paul Greengrass and Matt Damon,” says the actress.

“[My choices] come more and more down to the people I want to work with. But I’m a big fan of [all kinds of] movies myself. I’ve always loved going to the cinema. Good films come in all genres.

“And with ‘Lara Croft,’ the director is Roar Uthaug and I loved what he did with ‘The Wave,’ an ensemble [disaster movie] that came out last year.”

Fassbender is similarly ambitious, alternating the likes of “X-Men: Apocalypse” and the upcoming “Alien: Covenant” and “Assassin’s Creed” with more thoughtful fare such as “Steve Jobs” and “Slow West.”

“The main things that I choose are the director and the script,” says Fassbender. “I boil it down to those two things and it keeps it simple for me.

“The opportunity to do commercial projects came my way around 2010. The [question] was: Do I want to do [them] or not? And I did for various reasons.

“One of the reasons is I like to go see blockbusters and [cinematic] roller coaster rides myself. But I also like to see something that’s maybe smaller and has a social commentary.

“By doing the big films, it allows me to develop my own production company and get smaller films financed. It gives me more leverage.”