Undersea drone
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Undersea drones key to future of marine research

1 October 2013 Last updated at 00:08 BST

Scientists developing undersea drones say it is currently easier to communicate with the Moon than with the ocean floor.

While aerial drones have become almost commonplace - and controversial - unmanned undersea drones are still a work in progress.

One team in France hopes to introduce machines that will be able to undertake tasks from mapping to checking fish stocks.

But, as Christian Fraser reports from Toulon, getting the drones to communicate is a major obstacle.