Boyoma Falls, formerly known as Stanley Falls, is a series of seven cataracts, each no more than 5 m (16 ft) high, extending over more than 100 km (62 mi) along a curve of the Lualaba River between the river port towns of Ubundu and Kisangani (also known as Boyoma) in the Orientale Province of the Democratic Republic of the Congo.:Vol.Two,175 The seven cataracts have a total drop of 61 m (200 ft). They form the largest waterfall by volume of annual flow rate in the world, exceeding both the Niagara Falls and the Iguazu Falls.
The two major cataracts are the first below Ubundu, forming a narrow and crooked stream that is hardly accessible, and the last that can be seen and visited from Kisangani. At the bottom of the rapids, the Lualaba is known as the Congo River. A 1m-gauge portage railway bypasses the series of rapids, connecting Kisangani and Ubundu.