Nearly the entire search area has been scanned by the Bluefin-21, and there is no sign of Flight 370. But there are other unmanned submarines and submersibles waiting in the wings that may be able to find the missing plane. Gary Tuchman looks at these subs.
Anderson Cooper goes beyond the headlines to tell stories from many points of view, so you can make up your own mind about the news. Tune in weeknights at 8 and 10 ET on CNN.
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