SS Tanais (Greek: Τάναϊς), mistakenly referred to as Danae or Danais (Δανάη / Δαναΐς), was a British-built, Greek-owned cargo ship requisitioned by the German occupation forces in Greece in World War II.

[1] John Blumer and Co Ltd of Sunderland, England built the ship as Holywood for William France, Fenwick and Company of London.

She was raised, repaired and taken over by Mittelmeer-Reederei [de] (MMR), a company controlled by the German government that operated merchant ships in the Mediterranean theatre of the war.

On 20 May 1944, 276 Cretan Jews were arrested and loaded together with Greek underground fighters aboard Tanais which made her way to the port of Piraeus.

[8][9][10] On the morning of 9 June, the Royal Navy submarine HMS Vivid sighted Tanais 14 nautical miles (26 km; 16 mi) northwest of the islet of Dia at 35°35′N 25°11′E / 35.583°N 25.183°E / 35.583; 25.183.