what is the truth of the sky and ocean being blue?
The sky is blue primarily because of Rayleigh scattering. The oceans look blue and/or blue green for one of the following:
1. Rayleigh scattering to some extent.
2. Algae and other materials in the water. Some sections, especially those closer to shore, appear greener than others.
3. Many attribute the blue color to the fourth harmonic of the H-O-H stretching frequency at about 2.8 micrometers (fourth harmonic is about 700 nm which is in the red part of the spectrum; if the water absorbs red it reflects blue.)
Depending upon circumstances, I think all three contribute in varying amounts.