Actually, the DPRK fields about 25 antiquated subs, the newest being 20 odd Soviet Romeo's (like the one that washed up on a South Korean beach while dropping infiltrators a few years back. Seems the crew had plenty of U.N. food rations on board, as well.) They also have a handful of Whiskey class.
They do have a few hundred PT boats, with machine guns, and the occasional rocket launcher. They have some large hovercraft for infantry transport, and the classic landing ships for troops (some are so old they may be U.S. WWII vintage).
As I recall they have one or two large surface ships. I'm not a squid, but I've heard them assess the effective combat power of the North Korean Navy against ours as being negligible. Any squids care to comment?