Blue? I thought it was grey!

"In July the sun is hot. Is it shining? No it's not." (Flanders & Swann).

Because.

While you're at it, Tornado, how about telling us why the ocean is blue.

It reflects the color of the sky. [?]

The real answer (without getting too technical) is an extension of Lyns answer...ie...

Because...Neil Young says so:

"The sky is blue, and so is the sea"

("What is the colour, when black is burned, what is the colour, mmm" from "I am a child" by Neil Young).

Next question: Why do people ask "Why is the sky blue"?

Or... another question:

Why do the British never ask: "Why is the sky blue?" (Or Belgians, for that matter, in which cases:"Waarom is de lucht blauw?" or "Pourquoi le ciel est bleu?" or "Warum ist der Himmel blau?")

"It reflects the color of the sky".. yep, it seems like a good reason. Could explain why it's also grey from time to time. But doesn't explain why it's never white (not open water, I mean) since the sky is often white.

However.... the ocean is black when it's cold. It may be clear or overcast, but the ocean will be black on a cold winter day. Trees (conifers) are also black when it's cold, instead of green. So... reflecting the sky doesn't seem to be quite enough to explain it.

It's the color of H²O. Just as water is blue in the oceans.

It isn't blue. It only appears to be blue.

http://www.sciencemadesimple.com/sky_blue.html