Why is it difficult to transport goods on the rivers in Africa?

There are a lot of wild animals that will kill u

Because, In The Rivers Of Africa There Are Lots Of Dangerous Animals Such As, The Alligator, Crocodile, Lions, Rhinos, Snakes, Venomous Bugs And A Lot Of Dangerous Species. Also They Didn't Have Cargo Boats Like We Do In The U. S. A.