Here’s what happens when you strip off at the South Bank’s Finnish Rooftop sauna

Standing on the South Bank in a swimming costume is surreal. I speak from experience. It would be weird during the height of summer, when the edges of the Thames look like tiny beaches. But it’s even odder at 8pm on a Tuesday in the middle of November, when a bobble hat and thick winter layers would be more appropriate.

The reason I find myself very-nearly naked in the Queen Elizabeth Hall’s Rooftop Gardens is because the Southbank Centre have opened a high-rise Finnish Sauna, as part of their Wintertime celebrations and year-long Nordic Matters festival. The fact that I am nearly naked is important. Though many Finnish saunas traditionally are, this is not a nude sauna. Presumably that’s related to the fact that it’s elevated in full view of the entire South Bank, as well as Jimmy Garcia’s see-through igloos. Those poor punters didn’t part with £600 (yeah, that’s the minimum spend to get one) to see a handful of naked Londoners sweat profusely during their dinner.

Coats, scarves, shoes and socks come off the minute I step inside the temporary, wood-clad construction. We (a small group of up-to-16 heat-seekers) are given guidelines and a glass of water, before being introduced to our ‘sauna major’ Katie.

Then it is time to strip off. There are open-plan changing rooms and showers, with doors out onto the drafty deck of the rooftop gardens. Shivering, I’m fairly sure I flash a boob at an office block when one of my party opened the door back to reception, but this isn’t the time to be shy.

A couple of seconds inside the sauna and all chilly or self-conscious thoughts melt away. With two powerful stoves it’s dry and fiery, and can reach tropical temperatures of 90C. We learn about the social history of saunas (actually pronounced more like ‘sauw-na’ btw), the health benefits and löyly, the steam created when you throw water on the searingly hot stones, before sitting back to sweat it out and eye the view over the Thames.

When you need a break from the heat, there are buckets of ice-cold water outside for the brave/completely idiotic to tip over their heads (not for charity this time, guys). Instead, I pad out on to the decking for a couple of minutes in the bracing night air. Though I am wearing next to nothing, I’m not cold. In the centre of our busy, loud and stressy city, I feel glowing and relaxed, if a little exposed. It turns out getting your kit off above the South Bank is pretty liberating. You should try it some time.

The Southbank Centre’s Finnish Rooftop Sauna is open until Dec 30. Tickets start at £15. Find out more and book tickets here.