Ever since Hawaiians revived the ancient practice of surfing a century ago, and especially after Duke Kahanamoku—Olympic gold-medal swimmer and the original ‘Big Kahuna’—popularised it from Australia to California, riding the waves has been the quintessential Hawaiian sport. For surfers and spectators alike, there’s no place like the six-mile stretch of Oahu’s North Shore from Hale’iwa to Sunset Beach, where in winter, monster swells from Pacific storms rush unimpeded towards breaks in the reefs.