Vienna to Prague by boat

I don't think it is possible by boat. The Vltava river, which flows through Prague, flows north, into the Elbe. There is a range of mountains between the Vltava and the Danube. A lot of Danube cruises start in Prague, but you land to l Regensburg, on the Danube, where the boat part starts. There are several direct train connections per day between Prague and the Danube, at Regensburg, as well as several with one change in Schwandorf. There are also direct EC train connections between Prag and Vienna in about 5 hours.

Thanks. I suspected that it wasn't possible. We'll try the train and appreciate the information.

It is possible but it would be too long so I doubt any cruise ship would do it. It would be from Vienna down on Danube to the Black Sea then through the Mediterranean Sea to the Atlantic Ocean to the North Sea up the Elbe River and finally up the Vltava River to Prague.