Davey

I understand that there are non-metal materials that are "better" to use in this case, such as carbon and graphite for example. Due to these materials are more resistant to corrosion i assume. What would be my best choice of material for creating a long lasting circuit with the most power possible, through seawater?

"Very large electrode areas can be required" What do you suggest is very large? I want as much current to be passed as possible.

Is it possible to send current through seawater without electrolysis, including corrosion of electrodes and the production of H2O and Cl gas? Im thinking about using AC or alternating-DC polarities.