Schleswig

Schleswig is about an hour and a half north of Hamburg by car, up near the Danish border. It is the sort of town you stumble over by accident and then want to send all your friends to visit because it is so pretty. The famous Schloss Gottorf which is surrounded by water is in Schleswig. It is a museum now and has wonderful art exhibitions (which was why I was there).
But the town too is worth a visit. There is a yacht harbour and lots of wind to sail by.