How to transmit data underwater?

MarkT:

bigolbug:
dc42,
How would you recommend i amplify the received signal?

This paper has some interesting graphs of RF propagation in water: http://www.subseauk.org/documents/Wireless%20Fibre_Brendan%20Hyland.pdf

Hello MarkT, thanks a lot for your thoughts, very useful!
I am very interested in the file from Brendan Hyland that you linked before on dielectric curves of water, but unfortunately the company has pulled it down, and I cannot find it anywhere else. Would you have a copy of it?

Thanks a lot,
Angelo