The falls are located on the High Rhine between the municipalities of Neuhausen am Rheinfall and Laufen-Uhwiesen, near the town of Schaffhausen in northern Switzerland, between the cantons of Schaffhausen and Zürich. They are 150 m (450 ft) wide and 23 m (75 ft) high. In the winter months, the average water flow is 250 m³/s, while in the summer, the average water flow is 700 m³/s. The highest flow ever measured was 1,250 m³/s in 1965; and the lowest, 95 m³/s in 1921.
The falls cannot be climbed by fish, except by eels that are able to worm their way up over the rocks.
The Rhine Falls were formed in the last ice age, approximately 14,000 to 17,000 years ago, by erosion- resistant rocks narrowing the riverbed. The first glacial advances created today's landforms approximately 500,000 years ago. Up to the end of the Wolstonian Stage approximately 132,000 years ago, the Rhine flowed westwards from Schaffhausen past Klettgau. This earlier riverbed later filled up with gravel.
About 132,000 years ago the course of the river changed southwards at Schaffhausen and formed a new channel, which also filled up with gravel. Part of the Rhine today includes this ancient riverbed.
During the Würm glaciation, the Rhine was pushed far to the south to its present course, over a hard Late Jurassic limestone bed. As the river flowed over both the hard limestone and the easily-eroded gravel from previous glaciations, the current waterfall formed about 14,000 to 17,000 years ago. The Rheinfallfelsen, a large rock, is the remnant of the original limestone cliff flanking the former channel. The rock has eroded very little over the years because not too much sediment comes down the Rhine from Lake Constance.
The north side of the falls is a millsite. In the 17th century a blast furnace for smelting iron ore found in the limestone was built. It was in operation until the first half of the 19th century.
In 1887 the ironworks applied for permission to divert between one fifth to one half of the river's flow for electricity generation. The Swiss Alpine Club, the Schweizerische Naturforschende Gesellschaft (a nature group) and several scientific societies opposed the plan.
In 1913 an international competition was held for the best plan for a shipping route between Basel and Lake Constance.
In 1919, a company wanting to build power stations in northern Switzerland were told that any such station at the Rhine Falls "must serve the economic interest of the public".
In 1944, the Swiss Council of States granted permission to build the proposed power station. The permission was to become effective on 1 February 1948, with construction to begin in 1952. But in 1951, the Neuen Helvetischen Gesellschaft (New Swiss Society), under the leadership of Emil Egli, got 150,000 Swiss citizens to sign a petition protesting the project; among the signatories were 49 famous citizens, including Hermann Hesse and Carl Jacob Burckhardt. The petition not only scuttled the power station project, but effectively prevented all future hydropower and navigation engineering projects on the upper Rhine to the present day.
Today, the falls are still under consideration for hydropower projects, although there is little water in the Rhine to generate a significant amount of power. The greatest economic value of the falls is as a tourist attraction.
The nearest community is Neuhausen am Rheinfall, where tourists can also view the Schloss Wörth castle. Boat trips can be taken up the Rhine to the falls and the Rheinfallfelsen. There are also viewing platforms with a spectacular view of the falls built on both sides of the Rhine. These are reached via steep and narrow stairs. Guided tours of various lengths start from Schloss Laufen in Laufen on the Zürich side of the falls - a youth hostel is also located in Laufen. Various restaurants are located in Schloss Laufen, Schloss Wörth and the Rheinfall park.
The Rhine Falls are easily accessible by car, bicycle and public transport (the DB-Bahnhof "Neuhausen Bad Bf" and SBB-Bahnstation "Schloss Laufen am Rheinfall" railway stations). Large pay-parking lots are located in Neuhausen and Laufen.
Tourists have been awed by the Rhine Falls for centuries. In the 19th century, the painter J. M. W. Turner made several studies and larger paintings of the falls , and the lyrical poet Eduard Mörike wrote of the falls:
(Hold your heart, oh traveller, tightly in mighty hands! Mine nearly descended, shivering with pleasure. Restless thundering masses thrown upon masses, ear and eye, whither can they save themselves in such an uproar?)