The picture above shows the confluence of the three rivers in Passau-because the river is on the right hand side, the Danube is on the left hand side, and the Ilz River winds out from the middle of the houses on the left bank. The lack of three colors at the confluence of the three rivers is caused by the different water quality, density and flow velocity of the three rivers. These three rivers meet here, but their personalities are completely different. Because this river is a high landscape from the Austrian Alps, with high calcium content, it is light blue in color and runs very fast. The Danube is much more elegant and reserved, with slow tassels and deep rivers. Its color is deeper than that of the river, but its blue is always a legend. Ilz is narrow and curved, smaller than the two big rivers, but the color is the deepest of the three rivers. These three rivers have distinct colors, and obvious boundaries can be seen at the confluence.