Gaia at Greenbelt - why is it a blue planet?

The Gaia installation was at the Greenbelt Festival and was especially effective when illuminated at night.

They call us the blue planet. I have been very interested in Helen Czerski's brilliantly clear explanation of why water that comes out of a tap colourless actually looks blue when in the sea. It's in her book Storm in a Teacup. She explains that light entering the water is bounced around, heading mainly downwards but that eventually some is reflected back up out of the water and that is what we see. She explains that water molecules are able to absorb the other colours if the water is deep enough but not blue, so that is what we see. My next thing is to try to find out why water prefers to absorb red and not blue.