There’s a certain quasi-mystical attitude I encounter in some surfers that the sport is somehow more than just a sport, more attuned to nature, more pure. It’s always struck me as a little self-mythologizing, especially when you hear it here in New York, where most of the time you’re surfing man-made jetties, on constructed beaches, in neoprene wetsuits on fiberglass boards—and often taking the subway to get there. The great thing about Peter Westwick and Peter Neushul’s new book, The World in the Curl, is that they explore all the ways surfing has been influenced by—and has influenced—colonialism, war, capitalist industry, and other outside historical forces. It’s a perspective, they write, that “highlights the fact that, in many ways, surfing is an artificial pursuit, contrary to its romantic, natural image.”

Westwick and Neushul, who taught a class on the history of surfing at University of California, Santa Barbara, go into detail about the ways military technology revolutionized the sport. Surfers today forecast waves using technology first developed to help with the timing of amphibious assaults. They ride boards made of material produced for fighter jets. And they wear wetsuits invented for Navy underwater demolition crews.

The relationship between surfing and advertising goes back even further: from the beach boys at Waikiki surfing in front of hotels to entice tourists, to George Freeth, sent to the mainland as a traveling advertisement for Hawaii, ending up getting hired by Henry Huntington to surf in front of the tycoon’s new housing developments.

But the most profound part of surfing’s image reevaluated by Westwick and Neushul is the myth that the waves themselves are natural.

“You go to the beach and think you’re in a natural environment, when really the environment on almost every coastline in the U.S. has been engineered,” Westwick says in a phone interview with The Daily Beast. “Our main point is to open not just surfers' eyes but the general public’s eyes to how much engineering goes on to allow us to live on the coast.”

The more we’ve built on the beach, the faster those beaches have washed away, with the result that for the better part of a century we’ve been engaged in a perpetual construction project to build or rebuild beaches themselves, a project that’s had a profound impact on surfing. In the 1930s hundreds of thousands of cubic yards of sand were shipped to Waikiki’s beaches and dumped in front of the sea walls that had just been built to protect the new tourist paradise there. Plenty of surfers caught their first waves while on vacation at Waikiki, but all that new sand and all the diverted streams ended up filling in gaps in the reef and destroying old surf breaks.

“The Army Corps of Engineers,” Neushul and Westwick write, “has done more to shape surfing than any of the celebrated heroes of surf culture.” When I asked Neushul whether engineering has done more good for surfing than bad, he said coastal engineering has probably been a net benefit for surfers. Westwick and Neushul give the example of Maalaea, on Maui’s south central coast. Built in 1959, the long breakwater protecting Maui’s harbor created the break called Freight Trains, one of the fastest waves in the world. Environmental groups protested an expansion of the breakwater. They were joined by Save Our Surf, a local group of activist surfers who argued that an expansion would destroy the man-made waves. In the 80s Surfrider protested another proposed expansion for the same reasons.

As Westwick and Neushul point out, the fact that so many surf spots are man-made can put environmentalist surfer groups in odd positions, such as fighting against the removal of derelict oil piers near Santa Barbara because they create good surf. Are they first and foremost surf groups, dedicated to preserving surf spots, or are they environmental groups, trying to keep the coast as natural as possible? In 1989, Surfrider incurred a backlash when they proposed dropping giant polymer sandbags near Ventura to create a new surf break. Sponsored by Patagonia, the new spot would have been called Patagonia Reef had Surfrider not abandoned the project.

As surfing grew into the $10 billion industry it is today, surf groups have found themselves with a powerful and less ambiguous new weapon in their arsenal: economics. When Chevron wanted to build a rock jetty to protect an underwater pipeline near Santa Monica, Surfrider successfully argued that if the jetty destroyed the surf, Chevron would have to pay for an artificial reef. The California Coastal Commission agreed, saying Chevron would have to put $300,000 (the number of lost surfing days times the admission price to nearby Raging Waters theme park, bizarrely) toward a new reef. The reef didn’t end up working, but the decision meant that surf spots were effectively recognized as a natural resource that should be protected. In 2002, surfers stopped construction of luxury condos near Rincón, Puerto Rico, by arguing that they risked destroying a surf break that brought millions of dollars’ worth of tourism to the community. Recently, Surfrider invoked an economic argument against a proposed toll road near Trestles, off the Southern California coast.

Then there’s the human influence on the sea that surfers are probably more aware of than anyone else: sewage. A lot of older cities have sewer systems that take rainwater, sewage, and industrial wastewater in the same pipe. During normal times, it all goes to a treatment plant, but when there’s a storm, rather than overwhelm the treatment plants, it’s diverted straight into the sea. Unfortunately for surfers, storms bring the biggest waves.

Consequently there’s a sort of gallows humor about sewage: Westwick and Neushul point out that the break near the Hyperion sewage treatment plant in Malibu is fondly called “Shitpipe,” and a tube at—no joke—Sewers in Santa Cruz is called the “brown room” (normally it’d be the “green room”). Then there’s the Bondi Cigars, poo patrols, and all regional varieties of brown trout.

Westwick and Neushul note that historically there’s been a great deal of apathy in the surf community when it comes to political activism, but as beaches are closed more often for water quality problems and surfers are forced to confront the threat of skin rashes and illness, they may become the leading advocates for dealing with sewage that everyone else would prefer to forget. In this respect, they write, as with coastal development, “surfers are the perfect bellwether of human interaction with the environment.”

Surfing is special, Neushul and Westwick conclude, not because it has a uniquely pure relationship with nature, but because “the surf zone sits at the interface between an increasingly technological land-based civilization and the oceanic wilderness.” Understanding all the ways surfing is “artificial,” as they say, doesn’t diminish the sport; if anything, by the end of the book, it seems more fascinating.