A boat trip in Copenhagen could be a beautiful way to see most of the attractions. There are several trips offered:
50 to75 minutes long tours. There are 5 different lines; each of them rides different places.
The Netto Boats
This is a 60 minute long guided tour of the harbor and the canals.
Exciting and adventurous could be a kayak sightseeing tour with professional instructors.
This is a hop-on hop-off tour without guide. This bus sails along and between the coasts of Sealand and Amagar, the two islands.