When you see those wonderful river cruise images on PBS, complete with classical music and picturesque castles on green hillsides beside the tranquil Rhine, it probably doesn't occur to you that the river is climbing mountains, or running down them. But between Rotterdam and Basel, the river climbs over 800 feet.
Before the 18th and 19th centuries, commercial travel along the river had to contend with rapids, eddies and other obstacles. One treacherous area gave rise to the story of the Lorelei, a temptress on a rock who lured sailors to wreck their vessels at her feet. But as commerce grew and engineering developed, canals were built around some areas, channels shifted, and most importantly, locks were built to carry ships up the hill.
That's one of the unadvertised features of European river cruises: going through the locks. Many are transited at night, but a day-time passage can be fun and instructive to watch. And the experience isn't limited to the Rhine; all of Europe's navigable rivers have them except the Po in Italy. The Rhine has ten between the Dutch coast and Basel, the head of commercial navigation.
I got my chance to watch on a recent Viking River Cruise from Amsterdam to Basel; this lock is at Gambsheim, France, where the river forms the French-German border.
The locks, as you approach them going upstream, look like a bridge with barriers, clearly marked to make sure ship crews see them. As the ship approaches, the big gate opened, and we sailed into what seemed like a very narrow channel.
Pulling up very close to the wall makes it seem even narrower, but it turns out that the Rhine locks are wide enough for ships to share the lock, side-by-side. Ship lengths vary on the river, but maximum width is fixed: the locks are 24 meters wide, the ships don't exceed 11.45 meters. Amazingly, 22.9 meters of ship can share the 24 meter width, but it takes careful and skilled work.
That wasn't the only tight fit. The wheelhouse of our ship, which normally stands above the deck on a lift retracts into the deck to pass under the gate, the chairs are all folded over and the sun canopy that normally shades them drops nearly flat to the deck.
The back of the gate doesn't look as solid as the outside; it doesn't need to be solid, and lighter construction makes it easier to lift. It was fascinating to watch it slowly drop down behind us, until we were essentially floating in the bottom of a bathtub.
Once we were penned in, I moved to the front of the deck to watch us rise to the next level of the river. Those circles in the water are formed by the ducts that pull water into the lock. Some comes from the level above, but some comes from tanks below the lock that are filled when water is drained to lower ships going the other way.
And we're out. The lock is now ready for a downstream ship to sail in. When it does, the gate is raised to water level, and the water is drained to the lower level. The Rhine is a busy river, carrying lots of freight as well as cruisers, and the locks stay busy for hours.
Incidentally, for those who opt for the 'grand cruise' route from Amsterdam to Budapest, which transits the Rhine, the Main, the Main-Danube Canal and the Danube, there are 68 locks, as the ship climbs up one side of Europe and down the other!