Originally posted by twhitehead
Do you have any references? I believe its mouth is very deep but whether that can properly be called part of the river would be debatable.
After digging around on the internet I found this (rather unreliable) reference:
The claim seems to have been made in a documentary program based on new data. The poster in the above reference may have confused river depth with lake depth.
Wikipedia is silent about depth. There may be more reliable information on the online Encyclopedia Brittanica, but I can´t find out without subscribing (which you can do on a trial basis for free, but I don´t want the spam).