Blue, green, turquoise waters...Why does the sea change color?

Why is the sea sometimes green and blue in places?

A story of light...

Depending on the season, the weather and where you are in Destination Granville Terre et Mer, you’ll be lucky enough to see the sea change color. Sometimes gray, sometimes dark blue, sometimes light blue, green or turquoise, the sea puts on a magnificent show! But why does the sea change color? How can we explain this sublime shade of blue?

A landscape of

postcard

Lots of sunshine, fine sand, transparent water, turquoise in places – it’s the picture-postcard dream that we sometimes – indeed, quite often – experience at Destination Granville Terre et Mer. Some people think that the color of the sea is a reflection of the blue sky, but all you have to do is hold a little water in your hand to realize that it really is transparent. So the explanation doesn’t come from the sky, or just a little… It’s actually the light that penetrates the water. The sun’s rays are not just white: they are a visible spectrum of colors. As they penetrate the sea, these colors disappear. At first, the rays are yellow, then turn red, green and finally blue.

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View of the sea from the cliffside garden of the Christian Dior Museum in Granville — ©View of the sea from the Christian Dior garden|Alexandre Lamoureux

Light and

Depth

The hue we observe also depends on the depth of the sea. At the edge of the sea, it is not very important, which prevents theabsorption of the sun’s rays, which is why there is so much transparency… This transparency is also very visible on theChausey archipelago. The further offshore we go, the darker and darker the blue becomes. Sometimes, thewater turns green, due to the presence of phytoplankton containing chlorophyll, which absorbs the blue rays, bringing out another, more “vegetal” hue. The seaweed present in the Channel Sea of our Destination Granville Terre et Mer also influences the green color of the sea.

50 shades of

blue

“What’s important to remember is that the sea puts on its blue coat in good weather, when the sky itself is blue, and that it puts on its grey coat in bad weather, when the latter is also grey. Variations in depth at sea give rise to the different shades of color we observe.

Estelle, in love with the colors of Destination Granville Terre et Mer

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