Built to replace the troublesome Type 205 submarines of the West German Bundesmarine, which in turn had replaced the largely experimental Type 201 boats– Germany’s first class of submarines built after World War II– the Klasse 206 U-Bootes were interesting little subs.
The German Type 206s were basically the Volkswagen Beetles of the submarine word. However, they worked and remained in service for 35 years.
Just 500-tons submerged, they were 159-feet long but could remain at sea with their 22-man crew for weeks with the ability to deliver an impressive, one-time, spread of eight 21-inch torpedoes to a target, enough to sink a Soviet battlecruiser if needed. The first of the class, U13 (S-192) was commissioned in 1973 and the 18th, U30 (S-210) followed by 1975. Capable of an impressive 4,000-mile sortie, two of these Baltic u-boats even crossed the Atlantic unsupported, visiting New York City.
Check out this (German) video of one underway in 1975.
The Germans kept the class around through the Cold War, updating a dozen to Type 206A standard in the 1990s, and only fully retired the boats in 2010. Indonesia and Colombia picked up surplus models.