SS Donau was a Norddeutscher Lloyd (NDL) refrigerated cargo steamship that was built in Germany in 1929 and sunk in occupied Norway in 1945.

In 1928–29 Deutsche Schiff- und Maschinenbau built a pair of sister ships at its Vulcan shipyard in Hamburg for NDL.

Isar and Donau each had a single screw, driven by a three-cylinder triple expansion engine, augmented by an exhaust steam turbine that drove the same propeller shaft.

The combined power of Donau's engines was rated at 1,000 NHP[3] or 6,500 ihp, and gave her a speed of 14 knots (26 km/h).

As built, Donau's navigation equipment included wireless direction finding and submarine signalling.

[6] From 1930 until 1933 Donau made at least six voyages from Bremen to Los Angeles and San Francisco via the Panama Canal.

[2] On 17 August 1939 Donau left Hamburg bound for Los Angeles, San Francisco, Seattle, and Vancouver.

[2] On 21 September 1939 the Kriegsmarine requisitioned Donau, and ordered her to Hamburg to serve as a troop ship to East Prussia.

[2] In April 1940 Donau was one of six NDL ships that took part in Operation Weserübung, the German invasion of Denmark and Norway.

On 22 September she left Antwerp with the NDL ships Isar and Warthe on the orders of the head of maritime transport in occupied Norway.

[2] On 1 November 1940 Donau accidentally rammed the German training ship Bremse in the roadstead off Frederikshavn.

[2] From June to August 1941 Donau sailed in small convoys supplying German forces occupying Norway.

She sailed from Aalborg in Denmark and Stettin in Germany, making trips to Kristiansand, Kirkenes, Tromsø, and Honningsvåg.

[2] On 26 November 1942 Norwegian police, under Gestapo orders, handed 532 Jewish prisoners to the SS at Pier 1 in Oslo harbour.

Men and women were put in separate holds on the ship, where they were deprived of basic sanitary conditions and mistreated by the soldiers.