Kit Horn, a skilled surfer whose exploration of new surf spots along the California coast in the 1940s and 1950s — and later Oahu’s famed North Shore — helped the sport grow from a small subculture to an international pastime, died March 25 at his home in Encinitas, Calif. He was 80.

He had been ill with non-Hodgkin’s lymphoma for seven months, said his wife, Gwen.

At age 11, Horn began surfing in Santa Monica, when only a few hundred people rode waves in California.

With friends, including Buzzy Trent, Peter Cole and Peter’s brother Corny — all of whom would later be celebrated for riding big waves in Hawaii — Horn helped cultivate a surfing scene in Southern California, centered on Malibu, before tackling more fearsome waves in Hawaii.

“He didn’t achieve a lot of notoriety,” said Steve Pezman, publisher of The Surfer’s Journal. “In the inner circles of surfing, he was a well-respected waterman. He was a part of the crew that was pivotal in developing the sport and the culture.”

In addition to his wife of 59 years, Horn is survived by two daughters, Pamela Kelso and Lizabeth Lamberty; and two sons, Kirkand and Brit, all of whom live in California.