This is an interesting idea:
But I have so many questions... would you actually be able to hear the pings, or would they be in a frequency undetectable? How about the wildlife?
US team develop ‘final frontier’ 3D diver tracker
Scuba-diving groups needing to stay in touch or locate each other in an underwater emergency can struggle in lo-vis conditions, but researchers at the
divernet.com
But I have so many questions... would you actually be able to hear the pings, or would they be in a frequency undetectable? How about the wildlife?