They've already experience terrifying challenges involving wild animals in Africa and time consuming memory tasks in Europe, but a visit to Krakow, Poland will give the teams on The Amazing Race their most intense challenge yet.

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In a preview clip for the Friday, Nov. 13 episode, the teams will learn upon arriving in Krakow that they will need to descend 1000 feet below ground to complete a daunting task inside an old salt mine. And while there, they will be exposed to actual working conditions similar to what those who actually work in the minds deal with-an experience that will be sobering for them.

"Oh wow, that is heavy," Justin says in the clip as he and Diana complete the task. "If we had to do that for a full day's work? I couldn't."

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Diana also admits that the situation creeps her out a bit as well, because she's not a fan of the cramped and dark conditions.

"I don't like these types of environments," she says.

The true daunting nature of the challenge is only made more sinister in the clip when a voiceover cautions that the task is the most intense one the teams will face.

"What if you had to go 1000 feet underground, where there's barely enough air to breathe? Doing tough, back-breaking work? [This is] the most intense Amazing Race challenge so far," the voiceover warns.

The Amazing Race airs Fridays at 8 p.m. on CBS.

Tags: The Amazing Race CBS Reality TV