As a necessary piece of surfing equipment, the wetsuit, for a vast majority of surfers worldwide, is outranked only by the surfboard itself. Unlike boards, however, wetsuits have none of the mystique or glamour. "They are the airplanes of the surfing world," writer Ted Endo noted in 2012. "They  allow us to do something miraculous (survive cold water for hours on end) and yet they are completely taken for granted."

The wetsuit developed out of World War II-funded developments in plastics and rubber. In 1951, looking to make underwater work more comfortable and productive for Navy divers, U.C. Berkeley physicist and Manhattan Project veteran Hugh Bradner began testing prototype wetsuits constructed from various unicellular polymeric materials, including neoprene—a rubber created by DuPont years earlier. The military declassified Bradner's wetsuit designs the following year and encouraged commercial production, a decision that would eventually bring relief to surfers who were then wearing rubber caps and oil-steeped woolen sweaters as a defense against the cold.

Bev Morgan, a surfer-diver from Manhattan Beach, California, was given a copy of Bradner's report on wetsuit design and construction in 1952, and immediately began making suits for his diver friends. Morgan opened the Dive N' Surf dive shop the following year, and soon brought in fellow surfer-divers Bill and Bob Meistrell as partners; the Meistrells founded Body Glove Wetsuits in 1965 as a Dive N' Surf offshoot.

Meanwhile, surfer and window salesman Jack O'Neill, inspired after seeing neoprene foam carpeting along the aisle of a DC-3 passenger plane in 1952, began making and selling wetsuit vests out of his just-opened beachfront surf shop in San Francisco. O'Neill was the first to produce wetsuits specifically for surfers, and his company's technological innovations—particularly after the business moved to Santa Cruz in 1959—have in large part set the industry standard. (As did the company's marketing department, which in 1969 came up with the wetsuit tagline "It's Always Summer on the Inside.")

Surfing wetsuits didn't catch on until the late '50s, as the early models were constricting and often abrasive to the skin, and were also viewed by most wave-riders as sissified. The first three wetsuit styles to gain popularity were the tank-top short john, the ankle-length long john, and the front-zip long- or short-sleeve jacket, or "surf shirt"—also known as a "beavertail," for the rear-attached, wraparound codpiece flap that surfers generally left unsnapped and dangling.

Other types of wetsuits introduced over the years include the short-leg/short- or long-armed springsuit, the long-leg/long-arm fullsuit (the best-selling type of wetsuit, first made by O'Neill in 1970; called a "steamer" in Australia), and the hooded fullsuit. Wetsuit accessories such as gloves, hoods, and booties are used in colder climates.

It's often said that wetsuits work by allowing in a thin layer of water, which is then heated by the surfer's skin. While it is true that the wetsuit isn't watertight (unlike the tightly cuffed thin-rubber drysuit, developed during World War II and marketed to surfers without much success in the 1970s), its main objective is simply to provide a buffer zone between the skin and the ambient air and water. Air-bubble-filled neoprene rubber, lined on one or both sides with a "jersey" of nylon, polyester, polypropylene, or spandex, is the material that best combines insulation with lightness, flexibility, comfort, and durability—wetsuit development over the decades has been nothing more than a series of improvements, singularly or in combination, in each of these categories.

Increased warmth in large part has been a matter of better fit, which helps keep water from entering and pooling against the body. Comfort, flexibility, and lightness have been improved by advances in neoprene formulation and by combining neoprene thickness: the common "3/2" designation on a fullsuit, for example, means three-millimeter material is used primarily in the torso, with two-millimeter material used on the arms and lower legs; wetsuit thickness rarely goes above five millimeter or below one millimeter. Improved stitching, glued and taped seams, stress-equalizing patterns, and reinforced knees have all added to the wetsuit's durability. (Because saltwater is corrosive to rubber, a freshwater rinse after each use has always been the cardinal rule of wetsuit preservation. A full-time surfer in a moderate-to-cold region of the world can expect to get two seasons' wear out of a fullsuit.)

Ease of use has also been a perennial concern of wetsuit makers, especially with fullsuits. The fullsuit zipper at various times has been placed vertically up the front, along the spine, horizontally across the upper back, across the upper chest, and from shoulder to neck in a matched set. Velcro-sealed zipperless wetsuits, an updated version of a design first introduced in 1989, became popular in 1997. Extra-thick wetsuits have allowed surfers to explore for waves in Norway, Iceland, Russia, Alaska, and even Antarctica.

Wetsuits have at times been used as a surfing fashion accessory, particularly in the '70s and '80s: Hawaiian surfer Larry Bertlemann wore a bell-bottom long john in 1976; Mark Richards of Australia, world champion from 1979 to 1982, emblazoned the front of his suits with a Superman-copied MR logo; California trendsetter Danny Kwock had a neon-colored wetsuit wardrobe in 1980 that included a turquoise, cream, and magenta fullsuit. Santa Cruz aerialist Shawn "Barney" Barron took delivery on a custom-designed series of superhero wetsuits in the late '90s, and pro surfer Matt Wilkinson, from 2011 to 2013, delighted world tour fans by showing up at each event site with a custom wetsuit designed specifically for that location: dollar bills for New York, tie-dye for San Francisco, a matador print for Spain. But the vast majority of wetsuits produced over the decades have been black on black or black with dark blue accents.

Wetsuits overtook surfboards in the early '70s as the second-largest division of the surf industry, behind surfwear. Quiksilver, the world's biggest surfwear company, began making wetsuits in 1990, and Billabong soon followed. O'Neill has long been the best-selling surfing wetsuit manufacturer, with Rip Curl in second. As of 2016, cost for a 4mm men's fullsuit ranged from about $175 to just under $500.