I've been looking through the old newspapers until 1940 for mentions of Dragon Boat, to see where the races used to be held .
During the 19th Century, mentions in the papers refer to the races held in Canton rather than any in Hong Kong. In Canton each year, several rowers would drown, and there were often brawls between teams that would end in several more deaths.
From the 1900s, the races at Aberdeen start to get covered by Hong Kong's papers.
From 1919 - 1924, the Ming Yuen Gardens sponsor races. In most years the races are held off North Point in front of their site. The exception is 1921, when the races are moved to the Yaumati Typhoon Shelter.
1925: they're back to Aberdeen.
1926: Aberdeen and Shaukiwan.
1927: Aberdeen
1928: Praya East in Wanchai, and Ming Yuen Gardens at North Point
1929: Aberdeen, and Ming Yuen Gardens at North Point
1930: Cheung Chau
1931: North Point (planned, but cancelled when a boat sank on the way to the race) and Aberdeen
1932: Aberdeen. Report mentions an unusual addition, one boat with a team of "landlubbers" rather than the usual fishermen.
1933: North Point, arranged by the Chinese Civil Servants Swimming Pavilion.
1934: "off the Chung Shing Benevolent Society's bathing beach, Kennedy Town, and at the Chinese Civil Servants' Club's bathing beach.", Aberdeen, and "Shum Chun (British New Territory)".
1935: Aberdeen, Cheung Chau, North Point, Shum Chun
1937: Aberdeen, "Hongkong Chinese Civil Servants' Club at North Point, and the Chung Sing Club's swimming shed at Kennedy Town", New Territories
1938: Kennedy Town (Chung Sing Benevolent Society's Bathing Club), North Point (Hongkong Chinese Civil Servants Bathing Club)
1940: West Point (Chung Sing Benevolent Society's Bathing Pavilion)