The Great British Seaside is such a contradiction: it swells and swarms with people all summer long and yet, when the first frost sets in, these swathes of beautiful coastline become virtually deserted. Fossilised. Forgotten. Which is a shame, given the myriad benefits of bracing sea swims — or simply being close to a body of water — for our immune systems, metabolism and general mood. In search of this holy trifecta of wellness (Christmas is coming, etc) I find myself heading 250 miles south-west of London to Bantham Beach.