Swastika Harbour

This is what I found in the German Wikipedia which could fit:

image dated 1928-01-01, (public domain)

The "Bremerhaven" was the second vessel under this name built in 1920 by the shipping company "Norddeutscher Lloyd (NDL)" in Bremen/Germany.  This small steamer was used for the Brazil-service of the shipping company.
In 1928 the "Bremerhaven" was reconstructed for the East Asia Island Service of NDL, the ship was rebuilt for passenger services. In 1929, she ran for the first time from Hong Kong to Rabaul. By the end of 1936, the ship was flagged out to Hong Kong and renamed "Island Trader ". In 1938 she was withdrawn from service and used in Chinese coastal trade. In September 1939, the re-renamed "Bremerhaven" ship was put out of service in Dairen and sold to Japan in August 1940 .
Under its new name Teiun Maru she was lost after a mine hit on January 1, 1942, west of Luzon .

Another possibility would be the German warship "Gneisenau" which visited Hong Kong on March, 10th, 1938. But that tiny bit of ship that is visible doesn't look like a warship.

The Swastika flag came into law on 15 September 1935. For reference, the first German vessel to enter the harbour with the flag was the Norddeutscher Llyod liner 'Trier' on 29 September 1935.  China Mail 30 September 1935 refers.

The ship could be any german ship after 1935, passenger liner or merchant. The Norddeutscher Lloyd ran the asian route for passengers until 1939.

The German Swastika flag was hoisted on 1 March 1935 at the German Club in Hong Kong for the first time; according to the book: W. Sporleder, Hong Kong zu meiner Zeit. If Sporleder is right the German Clubmembers were ahead of the times (sadly). Because: "The Swastika flag came into law on 15 September 1935", as moddsey wrote.

There is a swastika engraved on a german gravestone in Happy Valley Cemetery. The location is:16F--/15/02. In Patricia Lim´s compilation her transcript has: "Hier ruht unser Kamerad / Paul Kurt Grohmann / geb 5 Januar 1909 zu Erlzachiem [?] / gestorben am Heomshall [?] / am 30th Dezember 1934 / illegible".  I could not figure out more of the letters when I made this photo of the grave in 2011. In English the text goes: Here rests our comrade Paul Kurt Grohmann, born 5 January 1909 - (the place is illegible) - died 30 December 1934 - (place illegible; but I am almost sure it must be Hong Kong). Grohmann can be found also on: www.hkmemory.hk (courtesy of Patricia Lim) where Grohmann is labeled as marine engineer of the merchant navy(?). On the picture the grave is the one in the back next to the greenery. I have no other informations about Grohmann.