A personal watercraft (PWC), also called water scooter or jet ski, is a recreational watercraft that a rider sits or stands on, not within, as in a boat. PWCs have two style categories, first and most popular being a runabout or "sit down" where the rider uses the watercraft mainly sitting down, and the watercraft typically holds two or more people. The second style is a "stand-up", where the rider uses the watercraft standing up. The stand-up styles are built for one rider and are used more for doing tricks, racing, and use in competitions. Both styles have an inboard engine driving a pump-jet that has a screw-shaped impeller to create thrust for propulsion and steering. Most are designed for two or three people, though four-passenger models exist. Many of today's models are built for more extended use and have the fuel capacity to make long cruises, in some cases even beyond 100 miles (161 km).

Personal watercraft are often referred by the trademarked brand names of personal watercraft by Kawasaki (Jet Ski), Yamaha (WaveRunner), Bombardier (Sea-Doo) and Honda (AquaTrax).

The United States Coast Guard defines a personal watercraft, amongst other criteria, as a jet-drive boat less than 13 feet (4 m) long. There are many larger "jetboats" not classed as PWCs, some more than 40 feet (12 m) long.