Comment Re:Why not use low earth orbit satellites instead? (Score 1) 25
The index of refraction of sea water is about 1.333. The index of refraction of most glass is between 1.45 and 1.95, or typically about 1.5. That corresponds to the speed of light in each medium being about 0.75 c and 0.66 c respectively.
TL/DR: the speed of light in sea water is faster than in glass.