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Through the poor winter weather, there’s one thing that many of us have been craving.
Sun, sand, and good old Vitamin Sea.
It’s a paradisal image: the golden sands of an otherwise empty beach, palm trees, a cocktail in hand, and the deep blue sea gently lapping the shore. But it’s one that helps many of us through the worst of the year’s weather, nonetheless.
So as you dream of the perfect coastal getaway, NASA have been trying to figure out something quite vital: where exactly is the ocean bluest?
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First of all, it’s important to understand why exactly the ocean appears blue. And here’s a hint: despite the common misconception, it’s not because the water is mirroring the blue of the skies above.
In fact, as NASA explain in an Earth Observatory article, our planet’s water appear blue thanks to the different wavelengths of light being absorbed or reflected. And in this, phytoplankton take a key role in determining whether water is blue or not:
“Sea water is often colored by phytoplankton—tiny plant-like organisms that form the center of the marine food web and play a key role in the global carbon cycle. Individual phytoplankton are tiny, but when they bloom by the billions, the high concentrations of chlorophyll and other light-catching pigments change the way the seas reflect light.”
If there is a particularly high concentration of phytoplankton, the water will appear green thanks to the chlorophyll they contain (just like high levels of sediment in water can make it appear brown).
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But what of blue waters? Well, as ocean scientist Joaquín Chaves-Cedeño explained, it’s no coincidence that the world’s bluest waters tend to be far away from coastlines or along the equator, where the surface water is rich with nutrients pulled up from the ocean’s depths by wind.
In the areas where coastal or trade winds aren’t so strong? Here, nutrients aren’t brought up to the surface, as Chaves-Cedeño explains of the South Pacific:
“With water flowing towards the center [of the South Pacific gyre] from all directions, literally piling up and bulging the surface of the ocean—albeit, by just a few centimeters across thousands of miles—gravity pushes down on this pile of water,” Chaves-Cedeño wrote. “This relentless downward push puts a lock on life…Layers of denser water trap the nitrogen and phosphorus-rich water at depth, keeping it too far down, where not enough light can reach it to spark the engine of photosynthesis that allows plants to grow.”
It’s not ideal for beach lovers of course, but the truth is, if you want the bluest waters you really do need to take to the seas.
Thought that was fascinating? Here’s another story you might like: Why You’ll Never See A Great White Shark In An Aquarium