It’s a freezing January morning—the kind where the air bites your arse and the sea looks like it’s plotting your demise. I’m in Glasthule, standing in front of what looks like a wooden barrel someone rolled off a Scandinavian hillside. Inside: people are sardined together, sweating through their togs, eyes half-closed in near-religious focus. Outside: dry-robed figures march toward the water like they’re heading to war. The heat spikes, and the sauna hisses like it’s alive.