This is coolbert:
Follow up to that prior blog entry, DPRK [North Korea] submarines on the move. MILITARY SOURCES IN ALL CASES SOUTH KOREAN MILITARY SOURCES.
Thanks to the tip from Freeper.
"Military Sources, 'About 50 N. Korean Submarines Left Their Bases...Can't be Located'"
"Dozens of N. Korean submarines left their bases at both Eastern and Western coast, and can't be located. Military are increasing their surveillance capability to track them, it is confirmed."
"That accounts for 70% of (N. Korea's) submarine fleet, which totals 70 ships. This is the largest rate of deployment since the Korean War."
"Military sources said, 'This is 10 times more than their normal deployment level. Dozens of them left their bases at both coasts, and we are unable to track them.'"
All those boats diesel/electric submersibles to include midgets and those designed for special operations type missions AND EVEN PLASTIC SUBMARINES.
From data as found at the wiki ONLY about one-third of those North Korean submarines a full-size deep water [pelagic] boat. Those of the Whiskey or Romeo class. Whiskey basically a clone of the World War Two German Type XXI class. Take it from there.