UUVs [unmanned underwater vehicles]  will probably play a bigger role as roving wireless nodes that increase the reach of underwater networks. The latest “glider” UUVs consume very little battery power…. Already, gliders serving as “mules” are descending to sensors in deep water where they acoustically collect information. They then ascend to the surface and send the data via radio, says David Kelly, chief executive of Bluefin Robotics, which provides UUVs to half a dozen navies.

The US Navy has ordered several gliders to form underwater mobile networks. With no engine noise, a stealthy “swarm” of gliders could monitor submarines and ships entering a strait, for example, surfacing to transmit their findings. Floating gateway nodes, dropped from the air, allow messages to be sent to submerged devices via low-frequency acoustic signals. This scheme, known as Deep Siren and developed by Raytheon, an American defence contractor, has been tested by the British and American navies.

“Underwater networking will put an end to the ‘data starvation’ experienced by submarines”.  The combination of acoustic signalling and UUVs, which can deliver data physically, will put an end to the “data starvation” experienced by submarines, as America’s submarine command described it in a report last year. Often incommunicado, subs have been condemned to “lone wolf” roles, says Xavier Itard, head of submarine products at DCNS, a French shipbuilder. His firm is developing a funnel-shaped torpedo-tube opening that would make it easier for a UUV to dock with a submarine. Being able to send messages quickly via acoustic networks would enable submarines to take on more tactical roles—inserting special forces when needed to a nearby battlefield, say, or supporting ground operations by launching cruise missiles from the depths.

The Soviet-built ELF radio system remains a “backbone” of Russia’s submarine communications, according to a Norwegian expert. But in a clear vote of confidence in newer technologies, America shut down its own system in 2004. Thanks to steady progress in undersea networks, what was once a technological marvel was, a US Navy statement explained, “no longer necessary”. Whether via sound waves, laser pulses, optical fibres or undersea drones, there are now better ways to deliver data underwater.

Excerpt , Underwater networking: Captain Nemo goes online, Economist Technology Quarterly, Mar. 9, 2013, at 7