It’s -4°C in Niseko, powdery snow is blowing almost sideways and I’m about to step outside—totally naked. I’m at one of the hundreds of outdoor onsens that dot Japan, where locals and tourists alike slip into pools of hot, cloudy water that’s naturally heated by volcanic rocks deep underground.
Tales of the miraculous powers of these baths have been told for centuries. More than 3,000 years ago, people in Matsuyama were said to have seen an injured heron return day after day to bathe in a hot spring until it was healed, and Japanese legends claim brave samurais recovered from their battle wounds after a long soak.
They may sound apocryphal, but it’s likely these stories contain a grain of truth. Scientific studies suggest onsens improve circulation and sleep, lower blood pressure, ease pain and generally boost human health. During last year’s Rugby World Cup, teams from around the world took to onsens after their matches, hoping the water would heal their battered and bruised bodies. Then there are the benefits to mental health—bathing in hot water is said to relieve anxiety and reduce stress.
(Related: Why A Mid-Day Onsen Dip Is A Good Idea)
But to experience this for myself, I have to brave the cold. Outside, three large baths of differing temperatures line a trail of wet stepping stones. I crack open the creaky door and make a dash for it, hopping stone to stone, slushy snow biting at my feet until—just seconds later, though it feels infinitely longer—I step, relieved, into the first pool.
It’s hot. Not get-me-out-this-second scalding, but still a shock to the system. I lie back, trying to relax. Ten minutes pass. Fifteen. Steam billows into the air. The snow slows and the towering, wooded mountain across the valley comes into view. There’s no sound apart from the trickle of the water bubbling into the pool and rustle of the wind through the trees. The heat is calming, the scenery pretty, but I fail to achieve the enviable zen of the monkish man floating a few metres away, his eyes closed in quiet contentment.
The second bath calls. It’s even hotter but, for reasons I don’t understand, this one feels better. Snowflakes coat my hair while, beneath the surface, my tense muscles melt as they would on a massage table. Stress floats away. My mind clears. Sitting there, warmth seeping into my bones, it suddenly all makes sense—this is why the Ottomans built marble-clad hammams, why Scandinavians flock to steamy saunas, why Russians bake in banyas, and why countless other civilisations have turned to heat for healing for millennia.
There’s only one pool left, just a few steps away. I slide in—and feel instant regret. It’s far too hot. So, with no embarrassment, I get out. Maybe this, too, is why onsens, hammams and other heat emporia are so popular—you’re in control.