Swimmer first, surfer always

He learned his speed in Honolulu Harbor, training in the Alakea Slip and diving for coins on boat days. On 11 August 1911 he swam 100 yards there in 55.4 seconds, 4.6 seconds inside the world record. The course had been measured four times, once by a professional surveyor, and five certified judges timed it. The AAU refused to ratify the swim, suggesting the judges had used alarm clocks. He re-broke the record under AAU supervision the following year.

Across Stockholm 1912, Antwerp 1920 and Paris 1924 he won five Olympic medals: gold in the 100 metres freestyle in 1912 and 1920, gold in the 1920 relay, silver in the 1912 relay, and silver in the 100 metres freestyle in 1924.

Surfing is heʻe nalu. It is Native Hawaiian and centuries older than him. Duke did not invent it and never claimed to; what he did was carry it from Waikīkī to the world.

On 24 December 1914, at Freshwater Beach in Sydney, he shaped a board from local sugar pine and paddled out. Australia dates its surfing to that afternoon. The board is still at the Freshwater club.

The board was a working tool as much as a sport. On 14 June 1925, off Newport Beach in California, he brought eight men alive off a capsized fishing boat on his surfboard. And at home he worked the beach at Waikīkī as one of the beachboys, the Hawaiian and part-Hawaiian watermen who taught visitors to surf and to paddle a canoe.