I ran across the article on Facebook a while back and kept meaning to do a post about the submarine. It seems I lost the original link. One of my first thoughts was maybe it’s a museum sub that was never stricken from whatever nation’s navy that owns it.
The answer may surprise you – https://nationalinterest.org/blog/the-buzz/taiwans-ancient-submarine-will-reach-astounding-80-years-19150. Here’s the information available on Wikipedia about the ROCS Hai Shih (SS-791): https://en.wikipedia.org/wiki/Hai_Shih_class. From the articles I found, it looks like Taiwan will be able to keep the submarine going through at least 2026. Here’s the history of the submarine when it was in the U. S. Navy: https://en.wikipedia.org/wiki/USS_Cutlass_(SS-478).
NavSource Online: http://www.navsource.org/archives/08/08478.htm
Taipei Times Feature: World’s longest-serving sub feted – www.taipeitimes.com/News/taiwan/archives/2007/04/17/2003356990
Wayback Machine links – two different defunct websites: https://web.archive.org/web/20091027055326/http://geocities.com/Pentagon/Quarters/1319/ and https://web.archive.org/web/20110906212322/http://usscutlass.org/
Various YouTube links:https://www.youtube.com/results?search_query=USS+Cutlass+submarine