For the last two decades, many reality shows have come and gone, but Survivor has managed to keep audiences enthralled. The concept of the show is simple: Take contestants who think they can outwit others on an island through challenges and social gameplay and have them vote each other off each week. The final three on the island then face those they’ve outlasted at the end — and the often-scorned Survivor failures then get to vote on who claims the $1 million prize.

We’ve seen the best and worst of the contestants on the show. But we can’t forget that many of the challenges they’re put through are quite dangerous. Here’s the riskiest one ever put on the show, and who’s testing it out beforehand.

The gameplay on Survivor has changed significantly over the years

The contestants on Survivor today often refer to “old school” and “new school” styles of gameplay, which is clearly a testament to how the game has changed over time. Looking back, the first season of the show seems quite innocent compared to the scheming that goes on now. And with the upcoming 39th season upon us, we’re sure we’ll see many young Survivor fans jump at the opportunity to blindside their competition, make fake idols, and outwit everyone on the island for their chance at the million dollars.

Host and executive producer Jeff Probst has also talked about the changing gameplay over the years. “And one of the single biggest changes in the game these past few seasons is, players are no longer afraid to change their mind at Tribal,” Probst told Entertainment Weekly. “If they hear something that sounds off, they immediately begin to reassess if they are doing the right thing. It’s imperative because you have to get through each vote and you want your alliance to survive as well because their game impacts yours.” Fans of the show are likely to see even bigger and bolder moves this upcoming season, too.

This challenge is the most dangerous

While Jeff Probst may be the executive producer and face of Survivor, HuffPost notes John Kirhoffer is the master game maker behind the scenes. The publication notes he’s been creating challenges for the show since 2000, and while he certainly has an incredible job, it can be stressful. And that’s especially true for one of the challenges he deems as the most dangerous.

“Spit It Out” is the challenge that makes Kirhoffer the most nervous. The Survivor Wiki explains three members of each tribe are strapped to a large windmill, and three other members of the tribe spin the windmill. At the bottom of the windmill is a tank of water that the contestants on the wheel are then submerged in. They must suck in a mouth full of water, spit as much water as possible into a tube, and do this enough times for the tube to fill and release a ball to continue on.

In addition to telling HuffPost this challenge is “unequivocally the most dangerous one,” Kirhoffer also added, “I was so nervous the whole time. We had people on the side, our safety team and our security, but, man, I was very concerned with that one. It worked great in Nicaragua [Season 21] and again in Redemption Island [Season 22], but we’ve never done it again just because my hair’s gray enough.”

The Survivor Dream Team tests the challenges beforehand

Before the contestants on the show give this challenge a shot, there’s a group of folks who give it a try beforehand and then run through the challenge again with the Survivors before they do it on the show. They’re known as the Survivor Dream Team. After Kirhoffer scouts out the landscape for where the next season of the show will be, he gets to work developing challenges (typically around 30 per season). And eventually, the hired Dream Team comes in to test out Kirhoffer’s new and old challenge creations.

“They rehearse every game to make sure it is fair, competitive and fun to watch, and they help us with figuring out all those little bits and pieces that we need to adjust,” producer Chris Marchand said. In a video, Probst also joked, “Beer is a big motivator for the Dream Team.” And if you can get a spot as a Dream Team member, it seems there’s a decent chance you can also obtain a full-time position as a member of the crew.

Tune in to Season 39 of Survivor on Sept. 25!

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