Chinese scientists have successfully sent information between entangled particles through sea water, the first time this type of quantum communication has been achieved underwater.

In this proof-of-concept experiment, information was sent across a 3.3-metre (10.8-foot) long tank of seawater, but the researchers predict they should be able to use the same technique to send unhackable communications close to 900 metres (0.55 miles) through open water.

"People have talked about the idea of underwater quantum communication before, but I'm not aware of anyone who has done an experiment like this," Thomas Jennewein from the University of Waterloo in Canada told Devin Powell over at New Scientist.

"An obvious application would be a submarine which wants to remain submerged but communicate in a secure fashion."

This is a big deal, because quantum communication - also known as quantum teleportation - promises to allow people to send messages that are protected from prying eyes by the laws of physics. It's the ultimate encryption.