Somewhat related, see underwater acoustic communication ('water modems'): * https://en.wikipedia.org/wiki/Underwater_acoustic_communication https://en.wikipedi

Somewhat related, see underwater acoustic communication ('water modems'): * https://en.wikipedia.org/wiki/Underwater_acoustic_communication https://en.wikipedia.org/wiki/Underwater_acoustic_communicat... In 2017, NATO formalized the JANUS standard (STANG 4748): * https://www.cmre.nato.int/rockstories-blog-display/398-janus-the-cmre-underwater-communication-protocol-becomes-a-nato-standard https://www.cmre.nato.int/rockstories-blog-display/398-janus... * https://nso.nato.int/nso/nsdd/main/standards/ap-details/1770/EN https://nso.nato.int/nso/nsdd/main/standards/ap-details/1770...