Tim Hughes talks to the people bringing the serenity of a Scandinavian spa to the country's music festivals

Picture the scene... dapples of sunlight play across a mirror lake, ringed by ancient trees in a secluded valley. As the sun goes down, strings of fairy lights twinkle their reflection across the water, and the trees glow with softy shades of blue and green.

Distant music and laughter are in the air –the sounds of a music festival in full swing – and beside the lake, groups of people in shorts and swim suits luxuriate in wooden hot tubs while sipping glasses of fizz.

Welcome to Wilderness festival. Or, to be precise, welcome to it's lakeside spa.

To those of us who still think of festivals as places to get hot and sweaty to your favourite bands, the lakeside at Wilderness comes as a revelation.

Hidden in a ravine, and draped along a land bridge between two pools at Cornbury Park, the spa is an oasis far from the beautiful chaos of the festival, with its music, drama and long table banquets.

And the people behind it are Bathing Under The Sky – purveyors of fine wood-burning hot tubs, which have graced festivals from Green Man, in the Welsh mountains, to Bestival on the Isle of Wight.

Founded in 2009, Bathing Under The Sky is a family business, run by a father, mother and two daughter team, near Cambridge.

Each hot tub is made by its team of craftsmen to its own high standards, based on a traditional Scandinavian centuries-old design. Each is made of western red cedar imported from Canada – the wood, highly prized by First Nations people, has a delicate scent and natural antiseptic quality.

There are showers – invariably the best on site for the initial wash and shampoo i handed out should revellers want to wash their hair afterwards.

And for anyone looking for a deep cleanse there is also a barrel sauna, also wood heated.

Bathing Under The Sky is the pet project of Slovakian Alexandra Weissova and her Czech partner Bart Juranek.

"It's our baby," laughs Alexandra.

"We wanted to run a business together to see how it went, but knew it had to be something we both like. It also had to be something different, that didn't require too much investment as we didn't want to borrow money.

"Then we met a woman who runs an organic farm in the Lake District and had a beautiful wooden Scandinavian hot tub, which had been made by some villagers. We loved it and thought we should try it.

"We rented it for four hours, which was too long, but that four hours changed our lives. It was so lovely with a beautiful view and cows grazing around us _ we both fell in love with it."

Realising that no one else was doing anything similar, they came up with the idea of their business – taking hut tubs around festivals and private events. Each tub is sold off at the end of each season, meaning they are all new.

"There was a lot to learn," she says. "The design is 300 years-old, but we made some practical changes. And we start each season with a brand new fleet so they are always shiny and pristine."

They have 35 tubs, with new items sold at £5,500 or pre-loved tubs £4,200 after one season. Each is reconditioned and comes in mint condition with accessories.

The Wilderness spa opens at 4pm today and runs from 8am-midnight for the length of the festival.

She goes on: "Wilderness is one of the nicest – but also the most technically challenging. We need 200,000 litre of fresh water and change water every 10 hours, so there's a lot of used water to deal with. We can't discharge it into the lakes and it's quite remote so we need to create an infrastructure with up to 6km of pipes.

And why are they so popular? "Because they allow people to take a break," she says. "It's very calming.

"When you are sitting in a beautiful wooden tub, it clears your mind and body from the inside. You see things from a new perspective, lose toxins – and clear that hangover

"It's a complete set-up for total relaxation and enjoyment of the outdoors. It's a unique and relaxing experience, and the perfect way to unplug from festival life."

More details at bathingunderthesky.com. Hot tubs at Wilderness are booked through the festival wildernessfestival.com. Wilderness runs from tomorrow to Sunday at Cornbury Park, near Charlbury