Today’s guest has swum the English Channel, conquered ice swimming world championships, and spends her days studying exactly what cold water does to our bodies and minds. Dr Heather Massey, from the University of Portsmouth’s Extreme Environments group, has found that wild swimming can do far more than give you a shiver—it can calm anxiety, lift mood, ease menopausal symptoms, and even help with depression.

Her research uncovers how cold water rewires the brain, builds communities, and may even protect us from ageing—while also revealing its dangers, from dangerous gasps to muscle fatigue and post-swim cooling.

So today, we’re asking: Is cold water swimming more likely to cure or to kill? And is it really the free ‘cocaine high’ anyone can get?