BlueDevil:"Chinese scientists have developed the first high precision underwater global positioning system (GPS). Tests have shown the new system can detect horizontal position within 5cm and depth precision within 30cm."
This is a joke, right? Last I heard there was no chinese GPS constellation in orbit. And the reported accuracy here is simply ludicrous. Even using WAAS, you're not likely to get better than 9 foot accuracy... that would be something like three HUNDRED centimeters.
This supposed chinese system requires four floating GPS receivers/transitters I suppose for triangulation, and the sonar system would be used to get precise depth values. I'm assuming the four floating buoys are fixed sites hooked hooked into something like a WAAS network in order to achieve this absurd 30cm accuracy.