Why do you see lightening on the ocean but do not hear thunder?

Answer 1

There is always thunder where there is lightning.  The lightning bolt will always create the compression/sound waves that create thunder.  On the ocean, lightning is visible for a much greater distance than the sound of thunder can travel.  Thunder's sound waves dissipate easily in the ocean and are estimated to be audible only at distances of less than 10 miles, whereas the ocean is optimal for the visibility of lightning and can be seen for many tens of miles.   Therefore the reason you see lightning but do not hear thunder is simply because the lightning is too far away from you.