Unterseebootsflottille), also known as Hundius Flotilla, was a front-line unit of Nazi Germany's Kriegsmarine before and during World War II.

Formed on 1 October 1938 in Kiel under the command of Korvettenkapitän Werner Hartmann, it was named in honour of Kapitänleutnant Paul Hundius, a U-boat commander during World War I, that died on 16 September 1918 after his U-boat SM UB-103 was sunk by depth charges from British steamer Young Crow.

It was disbanded in August 1944, when the last boats left the base for Norway.

At one point in their service history, each of the following boats served with 6th flotilla

This article about a specific German military unit is a stub.