The rocks along the Danube got funny names. One is called Napoleon's luggage, this one is called bee's nest or hollow stone.
On the second pic you see a number. It indicates the length of the Danube. For the Danube, the measurement is different. They begin at the mouth of the Danube and not, as usual, at the source. So don't wonder if you see here already more than 2000 km.
The Danube is much protected in that part, it is a nature reserve since 1978. There are only a few ships allowed. They have lots of restrictions: no pollution, interdiction to drive more often, having special motors which are not so loud as usual, ....
The place most of the tourists want to see is the so called Donaudurchbruch. It is the most narrow and the deepest part of the bavarian Danube. The rocks are limestone. In former times it was not so easy for the boatsmen to go through there. On the second pic you see rings in the rock, where the boatsmen tried to keep them.
In the general tips, I will describe a bit the trip on the Danube from Kelheim to Weltenburg. From the boat stop, have a look at the landmark of Kelheim, the Befreiungshalle built by Ludwig II. There is a small channel which leads into the Danube a s well.
The trip to Weltenburg lasts about 40 minutes for about 6 km and costs 7 € to Weltenburg and back. During the trip they give you informations about the Danube and the rocks along the way.
Favorite thing: There is a very small abbey, called Kloesterl. We didn't visit there, as it is usually empty nowadays. They told, that there is a church in the rocks. Sometimes someone is living there, when he wants to live lonely, as an hermit.