China has moved a step closer to creating a supersonic submarine that could travel from Shanghai to San Francisco in less than two hours.
In theory, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h, which would reduce the journey time for a transatlantic underwater cruise to less than an hour, and for a transpacific journey to about 100 minutes, according to a report by California Institute of Technology in 2001.
However, supercavitation technology has faced two major problems. First, the submerged vessel has needed to be launched at high speeds, approaching 100km/h, to generate and maintain the air bubble.
Second, it is extremely difficult – if not impossible – to steer the vessel using conventional mechanisms, such as a rudder, which are inside the bubble without any direct contact with water.