He was wave riding’s international ambassador. Duke’s 10-foot redwood board built in 1910, with his name across the bow is preserved in the Bishop Museum in Honolulu, on O`ahu.

“flamboyant shows at Waikiki.," wrote Brennan. "His spectacular rides kept the tourists talking”

Duke also surfed an obsolete sixteen-foot Koa-wood surf board that weighed 114 pounds.

"As Duke grew into strong, young manhood, he rode the waves the way he’d heard the ali`i warriors had ridden them proudly and handsomely. He began making the biggest boards to ride the tallest waves.

An expression heard the most, when he caught a wave, was his yell of "COMING DOWN!"

"Duke attained his greatest surfing satisfactions and some of his greatest achievements as a rider after his 40th year." — Tom Blake

Duke declared that even while he was still attending school, "I was fired up with a mania for improving the boards and getting the most out of the surf. I was constantly redoing my board, giving it a new shape, new contours, new balance. Others, too, began building new boards and experimenting in various ways. Everyone wanted to outdo the other. Apparently my enthusiasm was catching. No one was content to simply come up with the best possible board; everyone wanted to excel as a surfer and the rivalry was keen. I, for one, spent countless hours working at every phase of controlling my boards in the waves, trying new approaches, developing new tricks. When I wasn’t at school, I was in the surf."

It was in the period of 1909-10, that Duke began to get others interested in longer alaia style surfboards. No one besides Duke, apparently, ever got into the even longer olo-type boards until Tom Blake came to the Islands in the mid-1920s. "They grew from eight to nine feet or so," wrote Blake, in his book Hawaiian Surfboard, published in 1935. "Duke’s new one being ten feet long and three inches thick."

Duke wrote a front page article on surfing: "I have never seen snow and do not know what winter means. I have never coasted down a hill of frozen rain, but every day of the year where the water is 76, day and night, and the waves roll high, I take my sled, without runners, and coast down the face of the big waves that roll in at Waikiki. How would you like to stand like a god before the crest of a monster billow, always rushing to the bottom of a hill and never reaching its base, and to come rushing in for a half a mile at express speed, in graceful attitude, of course, until you reach the beach and step easily from the wave to the sand?"

In essence, it was Duke who brought surfboard riding to the Australian continent. Yet, Duke’s surfing in Oz was problematic at the beginning. He had not brought along a surfboard. That did not quash the deal. He just made one. Duke showed the crowd everything in the book," 1960s surf champion Nat Young wrote, "from head stands to a finale of tandem surfing with a local girl, Isabel Letham."

"But the point is," underscored Duke, "that the travel which my swimming afforded me also gave me the chance to demonstrate surfing wherever there was a satisfactory surf."

Assuming the 1917 date is correct, then Duke probably rode his longest wave on his 10-foot , 3-inch thick alaia style redwood plank.

To Duke, big boards were for big waves. "With his rare expertise and outstanding strength," Brennan wrote, "Duke handled it well in booming surfs. He used to defend his giant board and kid fellow surfers with, ‘Don’t sweat the small stuff. Reason? Because it’s small stuff.’"

Up until he was fifty, he remained a big-wave surfer.

Duke’s wave knowledge covered the wide spectrum of surfing, outrigger canoeing, and body surfing. Duke confirmed that many of the breaks now commonly associated with surfing were first tested by body surfers. Duke and friends would "body surf, like, Waimea and Sunset and those places… once in a while we used a board, but very seldom. And we don’t think of carrying a board with us because it’s kinda heavy and so we take a ride around island and look at these waves. And some of those waves on… the north side is terrific. And Waimea we used to go down there and ride body surf all the time."

"Well," Duke answered, "we older fellows we’d make it a great thing to take care of these kids. The youngsters we would send back into shore. I know a lot of the boys. Tough Bill, my brothers, and many of these fellows they’d come out and we’d know they can’t handle the big waves, so we’d send them back in shore. "And we’d say, ‘you stay there until you’re big enough and then you come on out.’ I’ve seen that done. And when they got a little older, and after three or four years experience out surfing in the canoe, then they got out by themselves and we let them go. But, we always tried to take care of them and didn’t care who they are, malahini [tourist, non-Hawaiian] or anybody. And every time we see them getting into difficulty in handling the board, or got into the wrong spot, we used to tell them, ‘you go over there, or you go over here, which is easier for you.’ And, they would take a lot of the information we give them, and that’s that."

"Well," Duke added, "to me I think we have to teach a lot of these kids first to be gentlemen; gotta be clean cut youngsters, you know; and keep the rule and never get in trouble; and try to help one another; and not try and hog the doggone waves, you know. There are so many waves coming in all the time, you don’t have to worry about that. Just take your time; wave come, let the other guys go, catch another one. And that’s what we used to do. We see a fellow’s coming in and we see some other fellow there first, we say, ‘now you’re here first, you take the first wave’ and that’s what we used to do."