China is developing a’supersonic’ submarine that could travel from Shanghai to San Francisco in less than two hours.

Researchers say their new craft uses a radical new technique to create a ‘bubble’ to surround itself, cutting down drag dramatically.

In theory, the researchers say, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h. 

The technology was developed by a team of scientists at Harbin Institute of Technology’s Complex Flow and Heat Transfer Lab. 

Li Fengchen, professor of fluid machinery and engineering, told the South China Morning Post he was ‘very excited by its potential’.

The new sub is based on Soviet technology developed during the cold war.

Called supercavitation, it envelopes a submerged vessel inside an air bubble to avoid problems caused by water drag.

A Soviet supercavitation torpedo called Shakval was able to reach a speed of 370km/h or more – much faster than any…