How are radio waves transmitted in water?

Question

Radio communication

I am watching the online broadcast with great interest:
https://www.youtube.com/watch?v=31vNARRU1SU
how is the data transmitted to the top?!!!
is it just the cable?
because in fact the water in this case is a HUGE screen ...
If I'm wrong about something or (most likely) I don't understand something correctly, correct me.
Thank you!

Answer 1

I don't think the camera itself floats in water. Most likely, the cables are simply connected to it - data is transmitted through them

Answer 2

Extra long waves as an option. They are poorly absorbed by water.
But in this case, the picture is most likely driven by cable.