The middle.
Danube is up to 8 meters deep in the upper part. It is much much deeper in the lower sections, especially in the Iron Gate Gorge, when it goes up to 54 meters.
Iskar river (if we dont count International river Danube)
The deepest point in the ocean is The Mariana Trench.
The deepest point found is 20 feet.
It's deepest point is about 706 metres, with an average depth of about 292 metres.
Java trench is the deepest point in the Indian Ocean.
The merced river is about 5 ft deep at its deepest point.
The deepest ocean is 36,200ft deep
Deepest Point in the Arctic OceanEurasia Basin: 17,881 feet / 5450 meters
Loch Ness is 788 ft (240 m) deep at its deepest point.
28,232 feet is the deepest it goes
The Pacific Ocean has the deepest point in the Challanger Deep.