Copenhagen, Denmark - Polarsteps
If you didn't get enough water with your GoBoat, then this boat tour is included with the Copenhagen Card. We always try to do at least 1 tour when on vacation so we can hear about the the culture and fun facts about the city we're in. This was a very informative tour and since we did it first thing in the morning it was an almost completely empty boat (it likely won't be at 3pm though...). We did see the back side of the Little Mermaid statue that people line up to see (as you can see from the photos).
I wouldn't say it's a must do but if you have the time, I'd give it a go.
Long Weekend in Copenhagen