Hamburg

Both North Sea and Baltic Sea beaches are reachable within an hour by car, railway, or bus.

Lübeck (Luebeck)
The city borders the Baltic Sea. The old city Altstadt survived from medieval times and is part of the UNESCO World Heritage List. About 60 km northeast of Hamburg, direct trains leave from main station every hour timetable (http://reiseauskunft.bahn.de/bin/query.exe/en?S=Hamburg&Z=L%FCbeck).
Lüneburg
A city in Lower Saxony, about 50 km southeast of Hamburg. Like Lübeck, Lüneburg's old town has kept a medieval look with old buildings and narrow streets. The town is situated in the beautiful Lüneburger Heide. South of Hamburg, direct trains leave from main station every hour (http://reiseauskunft.bahn...).
Sylt
An island in the north sea. This is where celebrities and wannabes spend their weekends. Trains leave at Hamburg-Altona station (http://reiseauskunft.bahn...). Planes from Fuhlsbüttel airport (http://www.syltair.de).
Helgoland
Germany's most off-shore North Sea island. Reachable by express ferry from St. Pauli Landungsbrücken (http://www.helgoline.de).
Altes Land
The region is the biggest connected fruit growing area of Central Europe and the one the furthest north in the world. Altes Land is an area of marshland south of the river Elbe in Hamburg and Lower Saxony around the old towns of Stade, Buxtehude, and Jork. A characteristic feature is the richly-decorated farmhouses with their elaborate gateways.
Ahrensburg
Ahrensburg is a northeastern suburb of Hamburg, situated in Stormarn district. Its outstanding sight is the Renaissance castle dating from 1595. Ahrensburg is easily accessible by car and train Hamburg public transport.
Sankt Peter-Ording
Germany's most popular tourist target by the sea. Features a broad surfer's beach and stilt houses. Easily accessible by car Autobahn 23, about 120 km and train (http://reiseauskunft.bahn...).
Kiel
Kiel's main tourist attraction is the "Kieler Woche" Kiel Week at the end of June, the largest sailing event of the world and one of Germany's largest festivals. Trains to Kiel leave at least once per hour from Hamburg main station (http://reiseauskunft.bahn...) and needs about an hour. A trip to Kiel on the Autobahn A7 takes about an hour, too.