UB-II class submersibles

UB-2 class (1915-18) German Empire – 30 submarines, UB-18 to UB-47 UB-45 underway in 1916 The UB-II class. Second part

German submarine u 3 hi-res stock photography and images - Alamy

Type II U-Boats (1935) - naval encyclopedia

H I Sutton on X: Royal Navy N-class submarine HMS Nautilus from #WW1. As far as I can find in my research, she was by far the largest submarine in the world

UB-II class submersibles

German Type Ub Iii Submarine: Most Up-to-Date Encyclopedia, News & Reviews

Type UB II boats - German U-boat Types - U-boat War in WWI

Type II U-Boats (1935) - naval encyclopedia

German submarine u 3 hi-res stock photography and images - Alamy

Submarines at War: From the Turtle to U-boats, Nuclear Submarines, and Unmanned Systems

UB-1 class submersibles (1914)

Admiral Nakhimov 2035 by planetrix15 on DeviantArt