The Rhine is a big river, not huge like the Amazon, but big enough for quite substantial ships to pass each other easily and with no drama. If the river is either too high or too low, the cruise ships can’t sail. Too high and we can’t get under bridges, too low and we’re in danger of grounding on a sandbar. The large number of river cruise ships is testimony to the fact that most of the time the Rhine is in that Goldilocks sweet spot of neither too high or too shallow.
The charm of a river cruise is you unpack once and your hotel room follows you across Europe, or up the Nile. When the conditions are not favorable, people who booked a river cruise end up on a bus tour. I’ll bet this leaves them mightily bummed as they have to pack up every day and get the luggage out to be loaded on the bus.
In all the river cruising we’ve done, we’ve only had a water level problem once. A cruise on the Elbe in eastern Germany was supposed to begin in Hamburg but there was insufficient water so we were bussed to Berlin and picked up the ship near there to go on upstream. It was okay, the Elbe is a much smaller river than the Rhine or Danube, more on a par with the Moselle.
We’ve briefly paused our journey, I believe to queue up to use a dock to reboard passengers who have gone to explore a castle on a nearby hill. Coincidentally we are stopped by an RV park with lots of small caravans (trailers), VW vans, and what appear to be class C motorhomes. By U.S. standards it doesn’t offer much, but here it is probably considered nice. I’m certain the people who do it enjoy it.
