Rebecca Mead on the Britons who are skipping the heated pool and rediscovering the pleasures of lakes, rivers, and seas, even in winter.

Everything you need to know about open water swimming, from techniques and training and to wetsuits and the benefits.

Lido, by Christopher Beanland, has arrived just in time, with many lidos now reopened – a perfect moment to delve into the beauty of outdoor swimming pools.