Talk:List of submarines by upgraded maximum stats/@comment-26800230-20150805000844/@comment-26705246-20150805005928

Doing runs to 1-5 C or D node and 250/130/200/30 are your best bets. Subs are an S rank drop and they have a low drop chance, same with construction. You just need to keep at it. I didn't get the regular 4 I-class subs until the Spring Event, where they were a common drop in one of the maps.

And I advise against grinding 1-5 for subs post HQ 80. Troll level increases by 500%. It took me 16 runs to clear it yesterday for the medal, pre HQ 80 the most it took was 5 (due to lucky opening torp on boss node). After 80, well, 7 of my turn backs were at the first node.