Inga Falls is the largest waterfall in the world by flow rate. Located on the Congo river, the falls are more than 2.41 kilometres wide and are the site of hydroelectric power plants which divert some 30% of the river's flow. The falls' estimated flow rate is approximately 25,768.33 cubic metres per second.

The waterfall with the most water volume is technically the Denmark Strait cataract, an enormous underwater waterfall located between Iceland and Greenland. It carries an estimated 123 million cubic feet of water per second, which is over 2,000 times the flow of Niagara Falls. On land, the title for the greatest volume belongs to the Inga Falls on the Congo River, though it is a series of rapids rather than a vertical drop. Among traditional "curtain" waterfalls, Niagara Falls has the highest flow rate in North America, while Victoria Falls in Africa is often cited for having the largest "sheet" of falling water during the rainy season. However, if measuring by purely uninterrupted vertical volume, the Guaira Falls once held the record until they were submerged by a dam. In 2026, environmental scientists monitor these flows closely as climate change impacts the glacial melt that feeds many of the world's most powerful cascades, particularly in the Nordic regions.