- Class: Tanker / supply ship
- Displacement: 7,021 tons
- Dimensions: 463 x 68 x 27 ft.
- Machinery: Geared turbines = 22 knots
- Complement: 130
- Builder: Blohm & Voss, Hamburg
- Launched: 1938
- Actions: Altmark was an unarmed tanker that served as a supply ship and repository for seamen captured by several German surface raiders. She sailed from Wilhelmshaven on 3 August 1939, refueled at Port Arthur, Texas, and then rendezvoused with the pocket battleship Admiral Graf Spee near the Azores on 28 August. After the latter was lost in December, Altmark remained in the South Atlantic for a month before sailing for home. She entered Norwegian waters in February with 299 British merchant seament aboard as prisoners. A diplomatic standoff between pursuing British ships and Norwegian vessels was resolved when destroyer HMS Cossack entered Jössing Fjord near Bergen on 16 February 1940. Her crew boarded Altmark and rescued the prisoners. Altmark was undamaged and allowed to proceed to Germany. She was later renamed Uckermark and assigned to support the battlecruisers Gneisenau and Scharnhorst and raider cruiser Michel. On 30 November 1942 she was berthed at Yokohama, Japan, when she blew up while under repair. The raider cruiser Thor which was along side was burned out and sunk as a consequence.