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"Don't ask me where I am, and even if you ask, I can't tell." This is from a well-known song of the Chinese submarine force. It sums up life on board: usually beneath the ocean's surface, away from prying eyes. The submarine is one of the most lethal weapons in or on the sea. Due to its stealth nature, missions are seldom reported. And once on a mission, all signals stop under water and the crew "disappears."