[Uncle Chip]

North Korea has probably dropped hundreds of mines to the bottom of the ocean floor. Upon activation and when an enemy vessel passes over it, a mine is released, electro-magnetically floats up to its target, attaches to the bottom of the passing vessel — and kaboom. It could be that simple.

[jhpigott]

I've read somewhere that this is a pretty active area for shipping. If that's the case, it would be hard to believe that it's mined extensively. FWIW - Hopes Fading for Survivors Noticeably, Minister Kim revealed during the parliamentary session that a North Korean spy plane was scouring near the NLL hours after the Cheonan sank. ... www.koreatimes.co.kr/www/news/nation/.../205_63219.html - 3 hours ago