Sometimes known, somewhat fancifully, as the "Venice of Prague", Kampa Island is a delightful area, cut off from the "mainland" by a mill stream known as the Devil’s Stream. Three mills still exist, of which two still have their mill-wheels in place.
It is from here that many of the boat trips along the Vltava leave.
Starting from the Old Town end of the Charles Bridge (Karluv most), crossing the bridge, turning left down the steps into Na Kampe, walking down Kampa through the "English Park", going back across the Legií Bridge (most Legií) and back past the Smetana Embankment (Smetanovo nábreží) makes a pleasant round trip.
This also gives access to Legií Island, which has fine views of the city.