[ThinkBeat]

Clearly the Ballistic Missile Submarines surfaces intermittently surface for comms as well? If not, they won't know when to set off their missiles making then not very useful as a deterrent

I have often wondered how close to the surface they need to get.

I would presume retractable antennas could be extended from a sub from a non-trivial depth. Or cable attached to buoys Or something much smarter that I have not thought about yet.

[yencabulator]

There's a couple of different "wake up" signals that can reach deeper into water. Their biggest limitation is very low bandwidth, so an attack sub will emerge (/send up a buoy on a tether) to get an updated tactical map.

https://hackaday.com/2020/07/15/the-many-methods-of-communic...

https://en.wikipedia.org/wiki/Communication_with_submarines

[ethbr0]

Also highlighting the E-6B Mercury (and the upcoming EC-130J), which among other communication options has a 5-mile (!) VLF antenna it deploys vertically in midair (!!) to establish limited-bandwidth communications with submarines.

https://m.youtube.com/watch?v=en-qekZX4ws

But I believe that's only good down to ~60 ft. Anything deeper requires the really long land-based ELF arrays.