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A ship carrying submarines will transport British scientists to the unexplored depths of the Indian Ocean, at the start of a three-year mission to unlock the secrets of one of the world's last great frontiers. The Oxford-based Nekton Mission scientists will go as deep as 300 meters down in crewed submarines. They expect to find new species as well as calculate the cost of human pollution and rising temperatures on a vast expanse of water along the shores of which 2.5 billion people live.