The robots in Dick's novel, loosely adapted by Ridley Scott into the film Blade Runner, were so similar to humans that when they went rogue, trained bounty hunters were called in to perform psychological tests to see whether suspected androids lacked human empathy.
It's painfully slow and complex work which has never been attempted before in these conditions: the small box-shaped robots, equipped with two claws, are operating in almost freezing water 5,000ft below the surface, in pitch black and strong currents.