Looking at North Korea's fleet was an incredibly interesting Wikipedia hole I went down earlier this year (link below). The mixture of indigenous and foreign built, looking at their age and getting an idea of when they built a lot and when they didn't, and looking at totals is interesting. Especially since it's supposed to be a cohesive fleet. This wikihole also pairs well with reading about their naval doctrine.
https://en.wikipedia.org/wiki/List_of_active_ships_of_the_Ko...