Underwater communication sport distance

Hi guys, I wanted to think about making something like this:

however I wanted to understand how to make wireless communication with the bezel which is always immersed in water

Easy way: use an antenna that stays out of the water, look at rsgroups forum section rc-boats how to do that.
Hard way: use sound.

I suspect they have the antenna at the top of the unit where it mounts to the board, so no water on top of it.