alt=|thumb|upright=1.2|The Rideau Falls (August 2025)
The Rideau Falls () are two waterfalls located in Ottawa, Ontario, Canada, where the Rideau River empties into the Ottawa River.
Description
The falls are approximately tall. They are divided into two by Green Island, which splits the Rideau River prior to reaching the falls. At the top of the falls, across each of these two branches of the river, is a stoplog dam that regulates the flow of the river and was formerly used to power industry in the area.
To the west of the falls is the headquarters of the National Research Council, to the east are the Canada and the World Pavilion and the French Embassy, and to the southeast (on Green Island) is Ottawa's Old City Hall.<gallery widths="200">
File:The Rideau Falls.JPG|The eastern branch of the falls, as seen from the Ottawa River
File:The Rideau Falls and the John G. Diefenbaker Building.JPG|The western branch of the falls (with Old City Hall in the background)
File:Ottawa013.jpg|Top of the dam and bridge over the falls
</gallery>
History
thumb|Rideau Falls in their original state, 1826
Samuel de Champlain described the falls as "...a marvelous fall...it descends a height of twenty or twenty-five fathoms with such impetuosity that it makes an arch nearly four hundred paces broad." The Rideau Canal, completed in 1832, was constructed to bypass these falls and the Hog's Back Falls.