Stonehaven Open Air Pool was opened in 1934 and is the the UK's only Olympic-size seawater lido. It is heated and open from late May to early September. Although Roger Deakin did not include it in Waterlog, it would be a perfect fit for the book. A brightly painted, welcoming place with a jolly cafe and huge local support - it is run by a Friends group - it is worth the detour (vaut le détour) as Michelin guides say.