Photo: M Swiet Productions/Getty Images

Have you ever wondered why these tropical waters are so blue? Here's your answer.

By Lauren Phillips

Call them what you want—azure, sky blue, cerulean, teal—but there’s no denying that the clear waters of the Caribbean are unbelievably blue. These gloriously clear waters draw millions of visitors each year to the tropical islands of the area, where the sand beaches are soft and pearly white and the waters are warm and perfect for snorkeling.

Related: 13 Places Where You Can See the Bluest Water in the World

But what makes these waters so clear and blue? There are actually a few reasons, but two major ones do the most to determine the sea's color:

1. The Caribbean is relatively shallow

You probably know why the ocean is blue—water molecules absorb wavelengths from the sun and reflect blue while the other colors are absorbed. Deeper water has a deeper blue color, closer to navy, as light cannot reflect off the seafloor; in shallower waters, this light is reflected, giving the blue a lighter color. The Caribbean is relatively shallow compared to other bodies of water, which allows sunlight to reflect off the seafloor and makes these waters appear lighter.

Related: The Best Overwater Bungalows in the Caribbean and Mexico

2. The Caribbean has a small phytoplankton population

Another natural phenomenon that contributes to the Caribbean Sea’s lovely clarity and color is its phytoplankton population. Or the lack thereof, in this case.

These microscopic organisms (also called algae) live in the water and contain chlorophyll, the same pigment that makes plants green. Large populations of phytoplankton add a greenish tint to water, resulting in bodies of water in shades from blue-green to true green, depending on how many and what kind of phytoplankton are there. Fewer phytoplankton mean bluer, more clear water, as in the Caribbean.

Other factors like pollution and silt and sand stirred up by storms can alter water color, but, for the most part, the Caribbean Sea maintains its characteristic light blue shade. Ready to see it for yourself?

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Photo: M Swiet Productions/Getty Images