Online, the cold plunge is a war: straight into the ice, or cool down first? In 1799 the Italian traveller Giuseppe Acerbi watched Finns come out of the sauna and roll in the snow, which he called going from boiling water into freezing water.

But the first minute in cold water is the dangerous one. You gasp, you breathe fast, your heart races. The advice in Finland: let your body cool first, walk in slowly, keep your head above water, and never swim alone.

So is the plunge worth it? In a small study, a 90-second dip in 20-degree water between two sauna rounds made the second round easier: lower body heat, lower heart rate. Healthier in the long run? Nobody has tested that. A good feeling, not proof.

The winter swimmers' last rule: just a dip is always enough.

Straight in, or cool down first?

Sources: Suomen Latu, winter swimming safety advice (suomenlatu.fi). G. Acerbi, Travels through Sweden, Finland and Lapland (1802), vol. 1, pp. 297-299. Owen et al. (2026), Experimental Physiology, doi:10.1113/EP093626. Datta & Tipton (2006), Journal of Applied Physiology; RNLI on cold water shock.
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