There are many, very many Christmas markets in and around Hamburg. As a sometimes already makes the decision difficult, what Christmas market you want to visit.
St. Peter Ording is 150 km North-West of Hamburg.
It takes only one hour to drive from Hamburg / Germany to the lake Schaalsee.
5 days on the Island Fehmarn
From Hamburg to Stralsund for 2 Days and one night staying on the Island Hiddensee in Kloster.