Artificially-generated waves made within a confined space, usually by flushing water from a holding tank, or by means of a series of paddles, or by pulling a foil from one end of the pool to the other. Wavepools have always provoked strong reactions among surfers. Some view them as a practical solution to crowded lineups, as the obvious way to increase the supply of "perfect" waves, and as a way to level the playing field for surfing competition. "As for the future of surfing," world tour competitor Richie Collins said in 1989, "all I gotta say is, why doesn't every country build an unreal wavepool?"

But many surfers—perhaps a majority—see wavepools as an automated perversion of a sport whose natural setting is its greatest attraction. "No matter how good technology gets at imitating Mother Nature," surf journalist Ben Marcus wrote in 1996, "riding waves in the chlorinated confines of a manmade tank will never compare to the raw experience of riding ocean waves over natural bottom contours." Wavepools use fresh water as a rule, but those built close to the ocean may use saltwater.

The earliest wavepools were built in Europe during the 1920s and '30s, and were for swimming only. Perhaps the best known was the Empire Pool at Wembley, London, which opened in 1934; it measured 200 feet by 60 feet, and had four electrically powered piston paddles in the deep end to rhythmically push forth mild swells that bubbled over in the shallows at the opposite end of the pool.

The 1966-built Summerland wavepool near Tokyo, Japan—another piston-type indoor pool, nicknamed the "Surf-a-Torium"—was the first to be used by surfers. Each hour the pool was cleared of swimmers, and boardriders were given 15 minutes in the barely-breaking waist-high waves. While the surf press described Summerland as "a forerunner of a fantastic era of artificial surfing," the Japanese pool—as with Wembley before it, and virtually all of the 500 or so wavepools built from the late '60s to the early '00s—was designed only to provide a safe and gently enhanced swimming experience for the general public; the inevitable result of bigger surf, wavepool owners understood, would be injuries and lawsuits. (Safety didn't get in the way of marketing, however, as most wavepools were given heavy-weather names such as Thunder Bay, Poseidon's Rage, and Typhoon Lagoon.)

Big Surf, the first American wavepool used for surfing was built in Tempe, Arizona, funded by hair-coloring giant Clairol, opened in 1969 and cost $2 million. The pool measured 300' by 400', and was set in a 20-acre Polynesian-themed complex located in the middle of the desert. Chest-high waves were created by dropping millions of gallons of water down a vertical 40-foot-high concrete chute and refracting the flow into the pool through underwater metal gates. Groups of surfers alternated with groups of swimmers and mat riders. Featured in the surf press and in surf movies, visited by world surfing champion Fred Hemmings, U.S. champion Corky Carroll, and dozens of other top American riders, Big Surf represents a media high point of sorts for early American wavepools.

Surf contest promotors have always been eager to use wavepools as a way to bring surfing to a larger audience, and contests have been held at locations around the world. Pro tour champion Tom Carroll won the 1985 World Professional Inland Surfing Championships, the first pro tour wavepool contest, at the Dorney Park Wildwater Kingdom in Allentown, Pennsylvania. At Disney World in Orlando, Florida, six-time world champion Kelly Slater won the 1997 Typhoon Lagoon wavepool contest, with Rob Machado taking the event the following year. Meanwhile, Australia's Matthew Pitts, a former world tour pro, spent nearly five years in the early and mid-'90s performing nightly as Sabu, the valiant sword-wielding surf prince, at the $100 million Ocean Dome wavepool in Miyazaki, Japan.

By that time, wavepool interest was diverted by a machine called the FlowRider, which created a stationary wave by shooting a thin layer of water over an inclined hard-rubber ramp, which in turn deflected the water into a wave—crumbly or tubing, according to the FlowRider operator. More often then not, a wavepool or a FlowRider setup was installed as part of a larger operation—a theme park, for example, or a hotel.

Wavepool technology took a big step forward with the development of "wavefoil" pools, which were both bigger than previous efforts, and worked by running a wave-making foil along a track attached to the bottom of the pool basin. A Spanish company called Wavegarden used the track-and-foil method to creat a long (nearly 20-second), hollow, tantalizing wave in a secluded Basque Country location; in 2015, the $12 million, 980' x 360' Surf Snowdonia pool opened in north Wales, using Wavegarden blueprints. Operating at full power, Snowdonia produced a wave about every 90 seconds. Pro surfers from around the world flew in to try Snowdonia, and were for the most part impressed with the shape of the wave, if not the size and power. However, the pool has been plagued by mechanical failures resulting in shutdowns.

In late 2015, the Kelly Slater Wave Company, fronted by the 11-time world champion, released a short video of its own track-and-foil wavepool, which created a bigger, longer, hollower, more powerful wave than anything yet produced by Wavegarden. Slater's wave was still in beta testing, the economic feasibility of his wave was open to question, as were all the old philosophical questions about artificial surf. But here at last was a self-contained man-made break to rival the best waves found in the ocean.