In which climatic zone of Africa do the deepest rivers flow?

Most of the large and deep African rivers flow in the subequatorial and tropical zones. For example, Congo, the deepest of the rivers on the mainland, originates in the tropical zone, then part of the current passes through the equatorial zone, and then the river again turns into the tropics. Another large river, the Nile, flows most of the way through the tropics. The same goes for rivers such as Niger, Zambezi, etc.