Yet another outstanding and informative video on a fascinating subject. I had understood that this communication was extremely difficult, but didn’t know exactly why or what alternatives existed. Thank you for answering my questions, Dr. Jones!

When I was working with gravimeter arrays about 20 years ago, I found it possible to use the vector sun moon tidal gravity signal to solve for position and orientation of the instrument using gravity. Which is not attenuated by the ionosphere or a conducting ocean, magma or intervening matter. I called it "gravitational GPS" and "gravitational compass". It is possible to use MEMS gravimeters for that now or atom interferometer chips, or several other kinds of detectors. I found more than a dozen low cost ways. As for communication using gravity. When I met Joe Weber at UMD back in the late 1970s, I asked him what he hoped for. He said that his gravitational detectors were intended for communication using 3D time of flight field interferometry. ( He did not say those words exactly, but that is how I would describe 45 years later). But he advised me not to follow him. Rather to follow his student collaborator, Robert Forward whose dissertation is titled "Detectors for Dynamic Gravitational Fields" Now i think Robert was partially responsible for LIGO but I never really bothered to check. I did not meet him until many years later, just before he died. Also, after many decades they now have high dielectric constant antennas that can synthesize and detect low frequencies so you do not need those giant transmitters, and it can be two way. The wavelengths, (using those kinds of transceivers or using array methods) that are larger than the earth would be great for scanning the early universe. From nanoHertz to GigaHertz. Putting low cost arrays on the Moon and Mars, can be as simple as setting them around and letting them self calibrate. Someone wrote me a few months ago about a small sensitive gravity gradiometer that could be adapted for drones and for orbit. An Earth Mars Moon baseline works for gravity too since the speed of light and gravity are identical. Not close, identical -- sharing the same underlying potential. I want to focus them on the sun. The gravity arrays can 3D image the interior of the sun and Moon and Earth. Lots of things that are possible, and not that difficult. But who has time? Add $Thanks and I can buy you a cup of coffee or tea. Richard Collins ,The Internet Foundation

Thanks for your review, I like your draw and tell technique.

Very interesting. I had no idea it was that difficult to transfer data that deep. I do work with many people that were in the Navy and I am sure they knew, but I was not aware. Thanks for sharing!

During the 1950s my uncle worked on just this problem. He was a civilian attached to the Royal Navy in Malta. He told me about his work, but said it was all top secret so could not talk about frequencies and powers. That let the cat out of the bag for me as then I knew it was radio communication. I also knew that seawater was a radio muffler, so deduced that the frequency would have to be very low, and that the aerials for transmission (I assumed they were under the surface) would have to be measured in miles. My uncle was awarded an MBE for his work.

SINS gear started in about 61 my father went under the icepack using that. Submarines have always relied mostly on dead reckoning and Sonar. I am a Merchant marine Master and teach navigation and dynamic positioning which uses ALL available means of positioning.

What a great experiment! I always wondered the same thing; movie and books often fake their way through with artistic license and used to make me question my own common sense when younger. Your straightforward experiment settles it, for anyone at any age. 🙏

I already know ocean is a bad mirror, no need to put my phone underwater ! thanks for the very clear explanation !

One of the receiving antennas on a sub is what amounts to an iron core loop. Note that as the depth increases so does both the attenuation of the signal and the attenuation of the noise. That's to say the s/n radio does not change that much. The reason for the locating Clam Lake transmitter on dry soil is so that the antenna is effectively higher above the conducting ground. Ideally the antenna would be 1/4 to 1/2 half wave above a conducting ground.

Toothed whales and dolphins (for example killer whales and bottle-nose dolphins) use echolocation for hunting and navigating, while baleen whales (for example humpbacks and blue whales) generally produce a series of sounds which are frequently termed 'songs' that are used for communicating.

I remember reading an article some years ago about vlf sub communication and I got the impression the antenna of the land based transmitter was submerged...

Very good explanation!

Beautiful presentation...Thank you Sir....

I learn so much from you. Thank you.

This is also why it is difficult to employ hi-frequency radio to gather data from electronic devices in the body, like ingestible or implanted monitors or defibrillators. It's still possible though, because RF techniques can be used to extract even tiny signals, and inside a body you only have like 10 cm of "saltwater" surrounding the device, plus it's only 1/3 as salty as the ocean. But submarines are thousands of meters under water in many cases. I think in "Crimson Tide" they have scenes where they have to raise an antenna in order to communicate. They also use very low frequencies such as 20 kHz that need huge antennas...

Excellent explanation. I understood the fact that radio couldn't penetrate the water without major issues which you addressed, but the details I was very rusty on. I'll definitely be doing some refreshing my knowledge and learning some new topics from your videos. Great job 👍

One ping only.

Subs absolutely do use radio. They tow really long antenna wires behind them and transmit VLF data messages.

omg the fact that you have to explain this demonstrates the dumbing down of the gene pool.

Finally a You-Tuber who is not afraid to say "miles" ! Too many just refuse nowadays and only say kilometers and it irritates the heck out of me when watching science videos.