You don't go sailing in New Zealand for endless blue skies and constant trade winds; what you get, instead, is a real adventure, which takes you back to nature, with days of variety and texture. Like the exhilarating sleigh-ride of a sail from Great Barrier to Kawau's dark sapphire-blue water, a perfect breeze, brilliant sunshine, dolphins, gannets wheeling overhead before divebombing into schools of silvery trevally.