Voorst, Netherlands - The lights dimmed and the crowd hushed as Karoline Kristensen entered for her performance. But this was no ordinary Dutch theater: the temperature was 80 degrees Celsius and the audience naked apart from a towel.

Dressed in a swimsuit and to the tune of emotional music, the 21-year-old Kristensen started her routine, performed inside a large sauna, with a bed of hot rocks in the middle.

For a week in September a group of wellness practitioners, called "sauna masters," are gathering at a picturesque health resort deep in the Netherlands to compete in this year's "Aufguss" world sauna championships.

The practice takes its name from a German term that loosely means "steam infusion" and refers to ritual preparation of a steam bath in a sauna.

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"Aufguss is an art. It's a theatrical way of doing sauna," said Lasse Eriksen, vice president of the Aufguss WM competition and jury member.

The competition has been steadily heating up as 16 nations vied for the coveted title in individual and team events.

Sauna masters "have to create good steam, show style and technique, and connect with the audience," he told AFP.

"That magic moment is when the heat, the smells, and the story combine to give the audience an incredible experience," he said.

The sauna masters are judged on several points: how they control the steam and temperature in the sauna, their "wafting" skills with one or two towels, and how their story draws in spectators, Eriksen said.

"Show Aufguss" started in Italy in 2009 and was rapidly spreading around the world, Eriksen said.

Currently most competitors are from European countries, but the art form also has a huge following in Japan.

Throughout the six days of the competition, the sauna masters gave 15-minute shows in the six-sided sauna theater, which sits up to 180 people per session.

The stories varied from tales about the universe, to powerful contemporary messages like Kristensen's and Czech sauna master Jiri Zakovsky's anti-war performance.

A major part of the shows included the masters' skill with towels, as they wafted steam over the spectators.

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Tricks included "the normal pizza," "the helicopter," "the parachute," and "around the moon," seeing competitors toss towels in the air and catching them, to the cheering of the audience.

One pre-requisite for the spectators is to be nude and dressed in nothing more than a towel for hygienic reasons.

It also helped the sauna masters, quipped Eriksen.

"Nervous theater performers are always told to picture their audiences naked. Well, here they cannot be nervous because this is the most naked place in the world!"

Inside the sauna, Kristensen poured scented water on the rocks releasing a cloud of steam, which she gently wafted with a towel as she whirled around the audience.

The Danish former lifeguard was doing her performance based on the real-life story of Syrian refugee swimmers Yusra and Sarah Mardini, who almost drowned at sea fleeing their war-torn country before competing at two Olympics.

At the end of her 15-minute set in the sauna, a voice asked Kristensen, now dressed in a T-shirt with the Olympic Refugee Team logo: "Was it worth it?"

She answered with an emotional "Yes!" before running outside to loud cheers.

"These masters are the best in the world, they are fantastic at what they do, and what a better way to relax than sit in the sauna and watch them," one audience member gushed, asking not to be named.

"I love it!" added Yvan Fermyn, a jury member from Belgium and long-time Aufguss participant.

Fermyn said a few months ago he was asked by a reporter whether he still enjoyed the spectacle after so many years. "It still gives me goosebumps," he replied.