Isle hell is breaking loose.

“Love Island,” Britain’s most controversial reality TV show, makes its stateside debut on CBS at 8 p.m. Tuesday.

How controversial is the British version? Controversial enough to routinely air footage of contestants in various states of undress throughout its five seasons — unmentionables on full display. Controversial enough to shoot couples actually getting it on — sometimes in front of their castmates, once on top of the sheets. (One of the contestants, 19 at the time, thought producers wouldn’t dare to show the clip.) Controversial enough that Zara Holland, Miss Great Britain 2015, was stripped of her crown after “Love Island” aired footage of her performing oral sex under the covers on a fellow contestant.

So, yeah. It’s pretty racy.

The now-notorious dating show, which will air five nights a week in the US, is like an extra-steamy mashup of “The Real World” meets “Big Brother.” Producers herd a dozen STD-tested singles into a luxury villa on a tropical island (this season, Fiji), cut them off from the outside world, squeeze them into a shared bedroom, hand out free condoms and issue a challenge: to lock down a partner and to stay paired up, no matter what.

Stuck single? Say goodbye — unless you’re adding fun drama to the show, in which case, you may be kept around for a bit.

This essentially leaves contestants with two options: to nurture one relationship amid the stresses of daily competitions, tempting new hotties and vote-offs — or to quickly, and perhaps sneakily, find someone new to couple up with.

The last pair standing wins the joy of shared partnership, and also a handsome cash prize. (American “Love Island” has not announced how much they’re paying victors yet, but the British show awards 50,000 pounds, or about $63,000, to the lucky lovers.)

After what they’ve been through, they deserve it. The challenges on “Love Island” aren’t your garden-variety reality-TV obstacle courses. In the past, the British series has instructed couples to identify each other by smell, make clay models of their partners’ genitalia and answer racy questions while hooked up to lie-detector machines. Some contestants get whisked away to Casa Amor — a nearby villa, packed with new eye candy — while their panicking partners sit at home.

But wait, there’s more! The show also enforces periodic “recouplings.” Contestants can choose to stay with their partners if they’re really head over heels — but if the feeling isn’t mutual, they may face elimination on top of a broken heart.

Model Eyal Booker, a contestant on the UK’s fourth season of “Love Island,” remembers the horror of a failed recoupling. The now 23-year-old fell hard for his “Love Island” girlfriend, Megan Barton-Hanson, and was sure they’d stay together through the team shift.

Sadly, they weren’t on the same page — and Booker, left partnerless, went home soon after.

“Looking back, maybe I should have not chased her as much,” Booker tells The Post.

Finding yourself suddenly solo is just one way to get kicked off the show: Audience members and fellow islanders can vote off contestants, too. (The UK show has an app; the American voting system hasn’t been announced yet.)

Of course, the producers have the ultimate say: Occasionally, someone who’s voted off returns, ramping up the drama. Fans say the unpredictable elimination rules add to the fun of it all.

Is your head spinning? Just imagine how the contestants feel, says Islander Idris Virgo, a boxer who was on the UK show last summer.

“Mind games are always being played by the other contestants,” says Virgo, who lasted all of four days on the island. “Everyone has their own game plan.”

These experiences, along with extreme social media exposure, may have tragic results: Just as suicide has plagued “The Bachelor” in the US, two former UK “Love Island” contestants ended their lives after their seasons wrapped.

Virgo has seen castmates reel from culture shock back in the real world. Because episodes shoot just a day or two in advance, “everything happens so fast,” he says. “Some of the contestants suffered from the constant attention from the media and the general public.”

Personally, he’s been glad to be able to lean on his fellow contestants.

“I made friendships in the house, and they have continued outside the house,” he says. “We support each other.”

Perhaps the biggest question about American “Love Island,” which is scheduled to run every weeknight through Aug. 7, is how much tamer it will be than its scandalous British cousin. American network broadcast standards (read: nudity policies) are much stricter than overseas, and “Love Island” executive producer David Eilenberg recently told Entertainment Weekly that “what we see visually will be a little different.”

But Booker — who has eyes and ears in the Island community — says he wouldn’t bet on a toned-down show.

“We’ll have to see,” says Booker, “[but] I think the US version might be crazier than the UK.”