If a medieval Danube boatman had been granted three wishes by a Danube goldfish, it is almost certain that among them would have been the removal, explosion, excavation, flooding, and total destruction of all the hazardous reefs. These rock monsters of Strudel, Wachau, and the Lower Danube lurked beneath the surface of the water for thousands of years, destructing ships and claiming the lives of countless boatmen. Then, somewhere, some sailor must have caught this golden fish, and during the river regulation, these rock formations were removed, blown up, excavated, or flooded. Except for a few, mostly harmless survivors.
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| The metamorphic reef of Schönbühel on 20 August (Kienstock 214 cm) |
There are not many of these survivors, and they owe their survival to the fact that they were not in anyone's way. Of the examples presented earlier, the Jochenstein rock of St. John of Nepomuk became the end point of a ship lock, The castle on the Wörth rock remained an island, but the Strudel rapids were flooded by the Ybbs-Persenbeug dam, Spielberg, once an island fortress, was swallowed up by the floodplain forest, the increasingly less modest Hunger Stone hid from everyone, the Babacai Rock on the lower Danube shrank, and nothing remained of the deadly rapids of the Iron Gates, where much more was destroyed. This list is not complete; it could also include the previously mined limestone cliff on the Mohács Island, but it is not worth mentioning those that tower high above the riverbanks, such as the monumental Devín castle hill at the mouth of the Morava River.
However, there is also a 'wild' rock on the Danube that has not yet been tamed by river regulation, despite its dangerous proximity to the center line of the Danube. What's more, this rock is located on the Austrian section of the Danube, which has been mostly converted into a shipping channel, where the river has been almost completely dammed. There were only two places in Austria where the Danube was left - so to say - untouched by hydroelectric power plants: the Donau-Auen National Park between Vienna and Bratislava, and the pictoresque Wachau between Melk and Krems.
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| The position of the reef during low water |
In Wachau, the dark metamorphic rocks of the Dunkelsteinerwald rise over the Danube in many places, often accentuated by various structures, forts, monuments, and crosses. In Schönbühel, a castle and a monastery crown the amphibolite rocks of the Czech massif, which extends into Austrian territory even to the right bank of the Danube, but at the foot of the castle, a cliff resembling the back of a drowned mastodon rises out of the Danube. Viewed from the right bank, this rock formation appears to be in the middle of the river, consisting of two distinct flat humps, which means that at certain water levels it is divided into two parts. This occurs when the water level measured at the Kienstock water gauge exceeds 262 centimeters, as on 22 August 2025, the reef was uniform. Roughly estimated, the Danube completely covers the reef at a water level of around 400 cm.
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| The reef and the navigation channel (source: Streckenatlas der österreichischen Donau 2024.) |
However, the view from the right bank is somewhat misleading, as the rock is not in the middle of the river (if it were, it would no longer be there), but closer to the castle, dividing the river into two parts in a ratio of approximately 1/3 to 2/3. Naturally, navigation takes place in the wider branch. The section below the castle is shallower, where the Danube foams and swirls in the rocky bed at low water levels, performing an activity that is economically immeasurable: it beautifies and diversifies the river.
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| The metamorphic reef of Schönbühel on 22 August (Kienstock 262 cm) |
Translated with DeepL.com
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