[jhpigott]

- that narrows it down alot. Looks like either a torpedo or a mine

“There is no possibility whatsoever that the ship sank due to an internal explosion or a collision with a reef. I guarantee that,” a navy lieutenant was quoted as saying by participants in a briefing session organized by the Navy’s Second Fleet Command in Pyeongtaek, Gyeonggi Province — the home port of the ill-fated ship.

http://www.koreaherald.co.kr/NEWKHSITE/data/html_dir/2010/03/27/201003270064.asp

[SunkenCiv]

Thanks jhpigott.