Hamburg Fuhlsbüttel Airport (HAM, tel. 507 50, www.ham.airport.de) is just 8 kilometres outside the city centre and has international and domestic flights. It currently connects to 52 cities abroad and is one of Germany’s top airports. International travel usually requires check-in 2 hours prior to departure and domestic travel one. While the lines are typically not too long, the check-in process can be, so allow yourself the full time.
To get there, take the U- or S-Bahn to Ohlsdorf and change to Airport Express bus N°110. A €2,50 single ticket is required for the trip. Allow a half hour travel time from the ciy centre.
Alternatively, hop on the Airport Express bus directly from Hauptbahnhof station to the airport. Tickets are €5 (children €2), €4 if you're in a group of six or more. Buses depart at 04:40, 5.00, 05:15, then every 15 minutes until 19:00, then every 20 minutes until 21:20.