Prague is a very interesting city. It combines antiquity with modernity. In Prague for the first time I saw that in the framework of the famous excursions "Hop on, Hop off" you can sail on a boat PrahaTrip.
The essence of “Hop on, Hop off” is as follows: you buy a ticket for the day and you can enter to leave the transport of this company wherever you want and how much you want - going around the sights at your own pace. I advise river cruises!