The name “Duke” is not a title, but a given name by his father, Halapu Kahanamoku, who was christened “Duke” by Bernice Pauahi Bishop in honor of Prince Alfred, Duke of Edinburgh, who was visiting Hawaii at the time of the elder man’s birth in 1869. The younger “Duke,” as eldest son, inherited the name.
Growing up on the outskirts of Waikiki (near the present site of the Hilton Hawaiian Village), Kahanamoku spent his youth as a bronzed beach boy. It was at Waikiki Beach where he developed his surfing and swimming skills. In his youth, Kahanamoku preferred a traditional surf board, which he called his “papa nui”, constructed after the fashion of ancient Hawaiian “olo” boards. Made from the wood of a koa tree, it was sixteen feet (4.8 m) long and weighed 114 pounds (52 kg). The board was without a skeg, which had yet to be invented. In his later career, he would often use smaller boards, but always preferred those made of wood.
On August 11, 1911, in an amateur swim meet, Kahanamoku was timed at 55.4 seconds in the 100 yard (91 m) freestyle, beating the existing world record by 4.6 seconds, in the salt water of Honolulu Harbor. He also broke the record in the 220 yd (201 m) and equaled it in the 50 yd (46 m), but the Amateur Athletic Union (AAU), in disbelief, would not recognize these feats until many years later. The AAU initially claimed that the judges must have been using alarm clocks rather than stopwatches, and later claimed that ocean currents aided Kahanamoku.
(Source: Wikipedia, via drartface-deactivated20120621)