We’ve all been there. You roll off the sun lounger, dip a toe in the pool, then a foot, then a leg, and as your stomach slides in… a gasp in case onlookers hadn’t clocked that the water is really cold. Invariably followed by a cocky, ‘it’s fine once you’re in’.

Author Chris Ballard

But what would you do if your pool was not 20 degrees, but below four? In this fantastic book about the power of really cold water, Chris Ballard finds out.

The Scandinavians have always known about the benefits of hot and cold therapy – and 5.5 million people live in Finland and enjoy 3.5 million saunas. But it is only in the last few decades that concerted scientific effort has been put in to discovering what happens to us when we plunge.

Studies have found that submerging in cold water improves your immune system, can cause a 250 per cent boost in dopamine, benefit cardiovascular health, and stabilise mood swings.