I can remember reading about these about 10 years ago when they were still a concept.
The article I read indicated that these underwater drones can be packed with 100 megaton charges.
Enough to wipe out an entire coastal region.
These kinds of James Bond - Austin Powers types of super terror weapons have been popping up in the imaginations of fearmongers for decades now. And only fools or those who believe in Hollywood too much actually believe them.
To start with, nobody has a "hundred megaton nuclear weapon". Nobody has ever had a 100 megaton nuclear weapon. Nobody ever planned on building a 100 megaton nuclear weapon. Ever.
The largest ever was 58 megatons, and that was almost 20% larger than the Soviets had estimated the blast to be. And yes, Product 602 was intended to be a 100 MT bomb, but even the Soviets realized such a weapon would not only have been a suicide weapon for the crew, it likely was undeliverable.
The thing was so massive that the Tu-95 that delivered it had several fuel tanks removed as well as the bomb bay doors. Meaning it would be almost impossible to deliver it anywhere very far outside of the Soviet Union itself.
Even at the height of the Cold War, most nuclear weapons were measured in kilotons, not megatons. And in the decades since actual nuclear weapon sizes have decreased, not increased. The era of requiring a fleet of bombers or a swarm of missiles to destroy a target no longer apply in the era of highly accurate modern precision delivery systems.
So to begin with, this is not real. Just the fact that somebody is even trying to claim it is shows serious signs of delusion.
Add to that, no nation is going to build such an insane weapon, then just park it in some random location to use "someday". One thing about every nation that possessed nuclear weapons, they do not let them out of their hands. The only time they are outside of "100 human control" is when they are being delivered to their target immediately before detonation. As in, on some kind of missile going to their target. And even then, there is somebody with a finger over the "self-destruct" mechanism to abort it.
And yes, this in reality has all the worst aspects of a submarine. Nobody on board to maintain it, and constantly being attacked by the hazards of that environment. And unless it is very deep underwater, anybody flying overhead can see the damned thing. And unless it is almost on the surface, you are not going to be able to communicate with it because things underwater really can't get any kind of radio signal.
That is why for contacting their subs at sea, for decades the US has relied on ELF. Extremely Low Frequency, as in 0 and 300 Hz. That kind of radio is almost perfect for contacting subs or anything deep below the surface. The wavelength is very large and can actually penetrate quite deep and can go a long distance.
The problem with ELF is however, it's only freaking 0-300 Hz!
For those scientifically illiterate, AM radio is between 535-1,705 kHz. FM radio is between 88 and 108 MHz. The WiFi equipment most in here would use for their internet is 2.4-6 GHz. And yes, the greater the wavelength, the greater the amount of data that can be sent through the frequency.
ELF is so slow and inefficient that for the US, it uses it as a way to contact the subs to tell them to raise to antenna depth. Basically sending out five character signals that takes about a minute to send all five. And if a five character set matches one assigned to a sub it notifies the Captain that there is some kind of transmission for them.
And that is just scratching the surface of why this is a completely idiotic concept.
