For a population so adeptly conditioned to cold weather, Finns are surprisingly good at taking the heat.
Tossing a large ladle of water over hot coals, a glistening, tattooed Nordic grins gleefully as our dark, charcoal-stained smoke sauna transforms into an angry furnace.
As steam singes my nostrils and beads of sweat form rivulets in every fleshy fold, I bolt for the door and wonder if basting tourists is all part of the entertainment.
There are 3.3 million saunas in Finland, more than one for every other person, but the majority are private. Helsinki's new Loyly (a term used to describe the steam that rises when you throw water on the sauna's rocks) represents a return to public, social spaces.
The wooden, steep-sloped structure, with a seaside bar terrace and open-air rooftop lounge, is also part of Helsinki's drive to embrace outdoor spaces and bask in the long, warm days of short but sweet summers.
Elsewhere, a carpark has been transformed into a pool complex and a new law has been passed allowing businesses to turn parking spaces outside buildings into temporary summer terraces. Subsequently, an apparently quiet capital is now outwardly effervescing with life.
I prevent my own blood bubbling so vigorously by retreating to Loyly's second, more sedate sauna, where horizontal pine slats act like Venetian blinds, revealing near-naked bodies descending a stepladder into the sea.
Closer to town, next to the port and fried fish stalls of Market Square, the Helsinki Allas Sea Pool opened on September 1.
Locals and tourists are making use of the dockside terrace, where filtered salt and freshwater swimming pools are suspended in the harbour next to segregated saunas. The idea for the complex, previously a tarmac carpark, was first touted 10 years ago and has been partly financed by crowdfunding.
Although paddling in the shadow of cruise liners is off-putting, the central location is proving popular, and owners plan to have a reserve of rentable swimwear for spontaneous sauna-goers.
If swimwear is not your thing, the Allas Pool hosts night-time skinny-dipping sessions whenever there's a full moon. The Finns have a reputation for knowing how to party - the Finnish word "kalsarikannit" means to get drunk at home in your underwear.
Along with cruise ships, sightseeing ferries servicing Helsinki's archipelago also leave from the port. Newly opened to the public this year is Vallisaari island, a 20-minute journey.
Once occupied by Russia and later used as a military base, it's now a nature refuge. I follow gently rising trails to lookout points and watch sailing boats weave through islands, etching spirals on a duck-egg blue watery canvas. Strict regulations govern Vallisaari; it's off limits from 10pm to 6am, although there is talk of opening a Tentsile hotel on the island next year.
The gravity-defying, British-made Tentsile Tree Tents, which are suspended between three trees and appear to levitate above ground, have developed a cult following in Finland, and adventure tour companies use them in Nuuksio National Park.
Dominated by forest-covered valleys and deep rocky gorges, the park, which is a 45-minute drive from Helsinki, is teeming with campers on a hot weekend in July.
According to the traditional Finnish legal concept of everyman's right, everyone has the right to roam freely through wilderness areas. Only campfire sites are restricted, although stores of free firewood make them appealingly convenient to use.
We hike alongside sparkling, tree-lined lakes filled with lilies, clambering over moss-covered granite boulders in the dark forest canopy, as shards of light skip across glistening red toadstools.
"The elves have been playing here," laughs my guide, Miki from Arctos Adventures, pointing to the disorderly mass of strewn stones.
Using thick pads to protect the trees, Miki sets up our tents next to the bathwater-warm Lake Kolmoislampi, while I wander off in search of blueberries.
"It's very Finnish to explore the forest alone and have an internal dialogue," explains Miki, and I enjoy every meditative minute of picking plump berries and staining my fingers purple in the process.
By midnight, it's still not completely dark. This is, after all, a Scandi summer.
Above me, wisps of treetops form charcoal scribbles in the sky, and in the distance I hear skinny dippers squeal as they splash in the lake.
Climbing into the Tentsile requires a big heave and a belly flop, but once inside, it's like sleeping in a spacious, supportive hammock. Air coolly circulates around my body and there are no irritating pine cones digging into my back.
Out here, surrounded by trees and toadstools, the freedom of movement lulls me to sleep.
By nurturing nature on their doorstep, Helsinki's city dwellers have struck upon a truly fine way to live.
Getting there: Singapore Airlines flies to Helsinki, via Singapore and Copenhagen, (connecting flights with partner airline Finnair).
What to do: Insight Vacations offers tours taking in Helsinki, including the 20-day "Grand Tour of Scandinavia".
Further information: See visitfinland.com.