Why is the sea blue? (02/02/09)

Anyone wondered why the deep ocean is blue? The water in a glass doesn't look blue... What's going on? Reflection from the blue sky? Since you guys work on the water you better go find out! Stephan in his 29th January blogpost gives a good article explaining how "Beautiful physics is hidden below the blue surface of the ocean.":

http://backreaction.blogspot.com/2009/01/water-is-blue-because-water-is-blue.html

There's also a good photo showing the difference between normal water (H2O) and heavy water (D2O). Deuterium is a heavy version of hydrogen in the water molecule, and makes for about 0.015% of all naturally occurring hydrogen in the oceans on Earth. In 1944 a commando sabotaged the ferry Hydro in Norway to stop the Nazis getting hold of a shipment of heavy water for their nuclear physics research:

http://en.wikipedia.org/wiki/SF_Hydro

They made a movie of it on DVD called "The Heroes of Telemark".