The Type UB I submarine was a class of small coastal submarines (U-boats) built in Germany at the beginning of the First World War. 20 boats were constructed, most of which went into service with the German Imperial Navy. Boats of this design were also operated by the Austro-Hungarian Navy and the Bulgarian Navy. In the Austro-Hungarian Navy, it was called the U-10 class.
The 1st U-boat flotilla also known as the Weddigen flotilla, was the first operational U-boat unit in Nazi Germany's Kriegsmarine (navy). Founded on 27 September 1935 under the command of Fregattenkapitän Karl Dönitz, it was named in honor of Kapitänleutnant Otto Weddigen. Weddigen, a U-boat commander during World War I, died on 18 March 1915 after his submarine U-29 was rammed by the British battleship HMS Dreadnought in the North Sea.
The 2nd U-boat Flotilla, also known as the Saltzwedel Flotilla, was the second operational U-boat unit in Nazi Germany's Kriegsmarine. Founded on 1 September 1936 under the command of Fregattenkapitän Werner Scheer, it was named in honour of Oberleutnant zur See Reinhold Saltzwedel. Saltzwedel, a U-boat commander during World War I, died on 2 December 1917, when his submarine UB-81 was sunk by a mine in the English Channel.
German submarine U-37 was a Type IXA U-boat of the German Navy (Kriegsmarine) during World War II. The submarine was laid down on 15 March 1937 at the DeSchiMAG AG Weser yard in Bremen, launched on 14 May 1938, and commissioned on 4 August 1938 under the command of Kapitänleutnant Heinrich Schuch as part of the 6th U-boat Flotilla.
German submarine U-625 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. The submarine was laid down on 28 July 1941 at the Blohm & Voss yard in Hamburg, launched on 15 April 1942, and commissioned on 4 June 1942 under the command of Oberleutnant zur See Hans Benker.
The 3rd U-boat Flotilla, also known as Lohs Flotilla, was the third operational U-boat unit in Nazi Germany's Kriegsmarine. Founded on 4 October 1937 under the command of Kapitänleutnant Hans Eckermann, it was named in honour of Oberleutnant zur See Johannes Lohs. Lohs, a U-boat commander during World War I, died on 14 August 1918 after his submarine UB-57 was sunk by a mine.
The 5th U-boat Flotilla, also known as Emsmann Flotilla, was a U-boat flotilla of Nazi Germany's Kriegsmarine during World War II.
SM UB-2 was a German Type UB I submarine or U-boat in the German Imperial Navy during World War I. She sank eleven ships during her career and was broken up in Germany in 1920.
SM U-47 was a Type U-43 submarine of the Imperial German Navy. She engaged in commerce raiding during the First World War.
The 18th U-boat Flotilla was a short-lived unit of Nazi Germany's Kriegsmarine during World War II.
The 19th U-boat Flotilla was a unit of Nazi Germany's Kriegsmarine during World War II.
23rd U-boat Flotilla was a unit of Nazi Germany's Kriegsmarine during World War II.
26th U-boat Flotilla was a training flotilla of Nazi Germany's Kriegsmarine during World War II.
32nd U-boat Flotilla was a training flotilla ("Ausbildungsflottille") of Nazi Germany's Kriegsmarine during World War II.
German submarine U-1163 was a Type VIIC/41 U-boat of Nazi Germany's Kriegsmarine during World War II.
German submarine U-771 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II. She was ordered on 21 November 1940, and was laid down on 21 August 1942 at Kriegsmarinewerft, Wilhelmshaven, as yard number 154. She was launched on 26 September 1943 and commissioned under the command of Oberleutnant zur See Helmut Block on 18 November of that year.
German submarine U-242 was a Type VIIC U-boat of Nazi Germany's Kriegsmarine during World War II.
UD-3 was an O 21-class submarine. The boat was laid down as the Dutch submarine HNLMS K XXV and renamed HNLMS O 25 but was captured during the German invasion of the Netherlands in World War II and commissioned in the Kriegsmarine.
UD-4 was an O 21-class submarine. The boat was laid down as the Dutch submarine HNLMS K XXVI and renamed HNLMS O 26 but was captured during German invasion of the Netherlands in World War II and commissioned in the Kriegsmarine.
Nazi Germany 
Kriegsmarine