👉 The fastest fluid is water vapor, which moves at speeds exceeding 1,000 meters per second (3,280 feet per second) in a vacuum. However, when considering fluid dynamics in Earth's atmosphere, the fastest is typically the jet stream, a high-speed wind current that can reach speeds up to 400 kilometers per hour (249 miles per hour). In liquid form, water can achieve speeds of about 100 to 200 kilometers per hour (62 to 124 miles per hour) in certain conditions, such as in ocean currents or during rapid tidal movements. But among all fluids under ideal conditions, water vapor's velocity in a vacuum is unparalleled.
