Flying Cloud was a clipper ship that set the world's sailing record for the fastest passage between New York and San Francisco, 89 days 8 hours. The ship held this record for over 135 years, from 1854 to 1989.

Flying Cloud was the most famous of the clippers built by Donald McKay. She was known for her extremely close race with Hornet in 1853; for having a woman navigator, Eleanor Creesy, wife of Josiah Perkins Creesy who skippered Flying Cloud on two record-setting voyages from New York to San Francisco; and for sailing in the Australia and timber trades.

Flying Cloud was built in East Boston, Massachusetts, and intended for Enoch Train of Boston, who paid $50,000 for her construction. While still under construction, she was purchased by Grinnell, Minturn & Co., of New York, for $90,000, (~$2.69 million in 2024) which represented a huge profit for Train & Co.

A reporter for the Boston Daily Atlas of 25 April 1851 wrote, "If great length [235 ft.], sharpness of ends, with proportionate breadth [41 ft.] and depth, conduce to speed, the Flying Cloud must be uncommonly swift, for in all these she is great. Her length on the keel is 208 feet, on deck 225, and over all, from the knightheads to the taffrail, 235— extreme breadth of beam 41 feet, depth of hold 21½, including 7 feet 8 inches height of between-decks, sea-rise at half-floor 20 inches, rounding of sides 6 inches, and sheer about 3 feet." Flying Cloud is often called an extreme clipper, as are many of Donald McKay's ships, even though her deadrise was only 30 inches.

Within six weeks of her 1851 launch Flying Cloud sailed from New York, rounded Cape Horn and made San Francisco in 89 days, 21 hours under the command of Captain Josiah Perkins Creesy. In July, during the trip, she ran 284, 374 and 334 nautical miles, a total of 992 nautical miles over the three consecutive days. In 1854 she beat her own fastest by 13 hours, setting a record that stood until 1989 when a contemporary 60 ft racing sloop, Thursday's Child, completed the passage in 80 days, 20 hours.

In the early days of the California Gold Rush, it took more than 200 days for a ship to travel from New York to San Francisco, a voyage of more than 16,000 miles, but clipper ships quickly cut that time in half. Surprise had set a record of 91 days, 21 hours on 19 March 1851, but Flying Cloud caused a sensation later that year, cutting a week off the record, and beating the three month barrier. Three years later, in 1854, she sailed the passage faster yet, setting a record that lasted for 135 years.

In newspaper accounts of the day, the clipper Andrew Jackson was acclaimed as holding the record passage to San Francisco. After careful scrutiny of the logbooks, Cutler concludes that a case can be made for either Flying Cloud or Andrew Jackson holding the record.

Andrew Jackson holds the record for fastest passage pilot-to-pilot, arriving at the San Francisco pilot grounds in 89 days and 4 hours. Because Andrew Jackson spent all night between the Farallon Islands and the Golden Gate awaiting a harbor pilot, some will consider this figure as the appropriate indicator of fastest sailing performance around Cape Horn.