[tom_mellior]

> As an example, Vienna-Budapest used to be served by hydrofoil for a 6-hour trip, which takes 2 and a half hours by train.

That sounds cool, but yes, not competitive unless you are looking for the enjoyment of being on a boat.

More practically, Vienna-Bratislava is 59 or 66 minutes by train, 75 minutes by boat. Depending on your exact departure and destination points, that might actually save a few minutes.

[JoeAltmaier]

Much of that hydrofoil 6 hours is probably spent at the 5 locks in the Danube along that stretch. And not even in the locks, but waiting your turn for the lock.

So, unless you are looking for a tour of the steel-and-concrete locks of the Danube, the hydrofoil trip may not be for you.