What role do the Boyoma Falls play in Congo River navigation?

The Boyoma Falls, a series of seven cataracts, serve as a significant barrier to navigation on the river system. They impede river travel for approximately 56 miles (90 km) between the ports of Kisangani and Ubundu.12

Because these falls make direct passage impossible, a rail line and road were constructed to bypass the cataracts, allowing for the transport of freight and goods between the two ports. Furthermore, the falls mark a critical transition point in the river's geography: they signify the end of the Lualaba River and the beginning of the Congo River proper, with Kisangani—located just downstream—serving as the starting point for the navigable middle section of the Congo.1234