Jack O’Neill, the Santa Cruz entrepreneur who opened one of the world’s first surf shops and pioneered the neoprene wetsuit that helped popularise year-round cold-water surfing, has died. He was 94.

The one-eyed surfing icon, who cut a rakish figure with his black eye patch and bushy beard, died peacefully of natural causes at his Santa Cruz home, waves lapping at his deck, his family said in a statement.

Known for his colourful personality and marketing genius, O’Neill began experimenting in the early 1950s with ways to insulate swimwear so he could stay in the frigid Northern California waters longer. Surfers at the time were using sweaters sprayed with oily water sealant, he recalled in one interview.

He tinkered with foam rubber but switched to neoprene, which was lightweight and flexible. A UC Berkeley physics professor, Hugh Bradner, had created a prototype wetsuit and tested it in icy Lake Tahoe in 1950. O’Neill claims he hit on the idea of using neoprene in wetsuits after seeing the material in the carpeting of an airliner.

Before his death in 2013, O’Neill’s chief rival, Bob Meistrell of Redondo Beach-based Body Glove International, also claimed to have pioneered the wetsuit. O’Neill and Meistrell threatened each other with lawsuits for decades.

Who actually invented the wetsuit has been described as the longest-running argument in surfing. What is not disputed is that O’Neill eventually developed an internationally known surfwear business after opening a small surf shop on Ocean Beach in San Francisco in 1952. Seven years later, he moved his family to Santa Cruz and opened a second shop.

He promoted his products with innovative ideas and marketing flair — dressing his children in his wetsuits and dunking them in ice baths at trade shows, according to Surfer Magazine. He also introduced the nylon jersey lining that made neoprene more comfortable against bare skin, the magazine said. And his trademark slogan captured his brand’s élan: “It’s always summer on the inside.”

By the 1980s, O’Neill had become the world’s largest recreational wetsuit maker and the O’Neill surf brand had gone global.

Ever the adventurer, O’Neill also was an accomplished sailor and aviator who flew hot-air balloons and invented the sandsailer, a sailboat on wheels that skirts the sand. He lost his eye in a surfing accident

“Of all the things that Jack is known for, I think his genius for marketing and promoting stood out,” surfing historian Matt Warshaw told the San Francisco Chronicle in 2012.

But O’Neill considered O’Neill Sea Odyssey, a marine and environmental education programme for children, his proudest achievement. The programme, founded in 1996, has taken nearly 100,000 children to the Monterey Bay National Marine Sanctuary aboard his 65-foot research catamaran to learn about the ocean.

“The ocean is alive, and we’ve got to take care of it,” O’Neill said about the programme, according to The Associated Press. “There is no doubt in my mind that the O’Neill Sea Odyssey is the best thing I’ve ever done.”

O’Neill was born in Denver and grew up in Oregon and Southern California, where he began body surfing in the late 1930s, according to the Encyclopedia of Surfing. He moved to San Francisco in 1949 and earned a bachelor’s degree in liberal arts at San Francisco State University.

He and his wife, Marjorie, who died in 1973, raised six children.