After dominating the Olympics, Duke went on exhibition tours, showing off his swimming and, crucially, his surfing. He famously gave demos in places like California and Australia, using massive, solid-wood boards. People on those beaches had never seen anything like a man gliding on water. He sparked the initial flame, creating the first real interest outside Hawaii. Those early seeds grew into the surf scenes in SoCal and Oz, which eventually exploded into the global culture we have. The dude was the original surf explorer.