Transitioning signals through different mediums (water and air)

One of my future projects are drones that operate autonomously (redundant?) underwater and communicate (anywhere in the world) through a buoy that then links to a satellite or larger local-surface-transmitter.

Just out of curiosity, I have read that in the water you want to use long wavelengths like AM, due to the density of the water.... and then using an air-based radio wave, transition from the two, drones communicate to the floating buoy then the buoy transmits to the local-long-distance transceiver.

Anyway, just curious

Any information would be appreciated

Quadrifilar antennas for satellites communication?

RF communications under water is tough due to loss. The longer wavelengths can penetrate farther, but they cannot carry as much information. You can setup an RF link over short distances, but you may want to consider an acoustic link for under water. Once the signal is received by bouy, it should be rather standard to communicate through a satellite.

Unfortunately, I don't have any further knowledge of how to do this. I have just been around others working this problem and become aware of their work and the solutions they were considering. Hope this was of some help!

Thanks rrumpf, it's more of an interest at this point but glad to have more information on the subject, thank you.