The Jet d'Eau (French pronunciation: ​[ʒɛ do], Water-Jet) is a large fountain in Geneva, Switzerland, and is one of the city's most famous landmarks, being featured on the city's official tourism web site and on the official logo for Geneva's hosting of the 2008 UEFA Championships. It is also one of the largest fountains in the world. Situated at the point where Lake Geneva empties into the Rhone River, it is visible throughout the city and from the air, even when flying over Geneva at an altitude of 10 km (33,000 ft).

Five hundred litres (132 gallons) of water per second are jetted to an altitude of 140 metres (459 feet) by two 500 kW pumps, operating at 2,400 V, consuming over one megawatt of electricity. The water leaves the nozzle at a speed of 200 km/h (124 mph). When it is in operation, at any given moment there are about 7,000 litres (1849 gallons) of water in the air. Unsuspecting visitors to the fountain—which can be reached via a stone jetty from the left bank of the lake—may be surprised to find themselves drenched after a slight change in wind direction.