Is this the new wave of submerged communications?
By: Kelsey Atherton  
The ocean hides what it contains, and it is in that hiding that submarines have their power. Lurking under seas, at first with just enough capability for an attack run and now with the ability to lurk for months at a time, submarines remain power out of reach, unseen until engaged in combat or resupplying in a friendly port. That stealth comes at a cost, however, besides the simple perils of existing underwater.
When submerged, submarines are more or less on their own until they resurface again, since radio waves do not travel well through seawater. Or they are for now. New research by MIT, presented at a conference in late August, devised a way for submerged submarines to communicate wirelessly with people on the surface by combining hydroacoustics and acoustic radars.
https://www.c4isrnet.com/c2-comms/2018/08/28/mit-discovers-way-for-submarines-to-talk-to-drones/
