History
German Empire
Name	U-121
Builder	AG Vulcan, Hamburg
Cost	6,177,000 Goldmark
Yard number	95
Launched	20 September 1918
In service	9 March 1919
Fate	Surrendered on 9 March 1919 to France Sunk as target off Cherbourg, 1 July 1921
General characteristics [1]
Class and type	Type UE II submarine
Type	Coastal minelaying submarine
Displacement	1,164 t (1,146 long tons) surfaced 1,512 t (1,488 long tons) submerged
Length	81.52 m (267 ft 5 in) (o/a)
Beam	7.42 m (24 ft 4 in)
Height	10.16 m (33 ft 4 in)
Draught	4.22 m (13 ft 10 in)
Installed power	2 × diesel engines, 2,400 PS (1,765 kW; 2,367 shp) 2 × electric motors, 1,200 PS (883 kW; 1,184 shp)
Propulsion	2 shafts, 2 × 1.61 m (5 ft 3 in) propellers
Speed	14.7 knots (27.2 km/h; 16.9 mph) surfaced 7 knots (13 km/h; 8.1 mph) submerged
Range	13,900 nmi (25,700 km; 16,000 mi) at 8 knots (15 km/h; 9.2 mph) surfaced 35 nmi (65 km; 40 mi) at 4.5 knots (8.3 km/h; 5.2 mph) submerged
Test depth	75 m (246 ft)
Complement	4 officers, 36 enlisted
Armament	4 × 50 cm (19.7 in) bow torpedo tubes 14 torpedoes 2 × 100 cm (39 in) stern mine chutes 42 mines 1 × 15 cm (5.9 in) SK L/45 deck gun 494 rounds

SM U-121^{[Note 1]} was a Type UE II long-range minelaying U-boat of the Imperial German Navy intended for service in the Mediterranean. The Austro-Hungarian Navy allocated her the number SM U-84. She was built at Hamburg, Germany, by Aktiengesellschaft Vulcan and launched on 20 September 1918. Incomplete at the Armistice she was never commissioned in the Imperial German Navy but surrendered to the Allies at Harwich on 9 March 1919. Handed over to France, she was sunk as a gunnery target off Cherbourg on 1 July 1921.^[2]

• Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.

v t e Shipwrecks and maritime incidents in 1921
Shipwrecks	3 Jan: UB-88 6 Jan: USS Coast Defense Battleship No. 2 20 Jan: HMS K5 31 Jan: Carroll A. Deering January (unknown date): SMS Baden, HMS Europa, Hewitt 9 Feb: HMS Hydra 21 Feb: USS Woolsey 3 Mar: Hong Moh 4 Mar: Carroll A. Deering 13 Mar: Leonita March (unknown date): USS Conestoga 13 May: Miztec 14 May: Wollongbar 23 May: USS Granite State 26 May: Esperanto 7 Jun: U-151, UC-97 21 Jun: USS G-1 22 Jun: U-177 24 Jun: HMS K15 26 Jun: Fitzroy 30 Jun: Mopang, U-152, U-153 1 Jul: U-121 11 Jul: General Pershing 13 Jul: SMS G102 15 Jul: V43 18 Jul: Frankfurt 21 Jul: Ostfriesland 22 Jul: U-140 16 Aug: Baden 26 Aug: City of Brunswick 3 Sep: Abessinia 26 Sep: USS R-6 27 Sep: USS Alabama 7 Oct: USS Herreshoff No. 321 8 Oct: Rowan 3 Nov: Carrier Dove 30 Nov: Guvernøren 1 Dec: USS DeLong 7 Dec: USS S-48 30 Dec: HMS Prince George Unknown date: Equity, Rüsumat No 4, U-86, U-161, UB-122
Other incidents	29 Jan: España 18 Apr: Iron Monarch May (unknown date): USS R-14 8 Jul: Western Comet 19 Jul: Submarine No. 24 27 Jul: Animoso 17 Aug: Maurice Callot 19 Aug: King Orry 29 Aug: Maurice Callot Unknown date: USLHT Azalea
1920 1922