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How much coastline is there on Earth?

Happy birthday to my cousin who wasn't super picky about her Doodle, but did mention the beach. A place she visits and from what I can tell, has a really good time when she's there! I can attest not all beach are created equal. In fact, I would say I'm more picky than most when it comes to beaches... I'm not a huge fan of sand, so it has to be REALLY nice for me to want to go. Others I know, my cousin included, are just fine with a mild weather beach with sand grains similar to course sea salt... good for them I suppose, opens up many more opportunities to enjoy "the beach", that's for sure! So, exactly how much beach is there?

As I'm sure you might know, about 70% of the Earth's surface consists of water. The oceans are a key element for the existence of life on Earth. 97% of all the water on Earth, and 99% of the habitable space on this planet, is in the ocean (yes, that's why we have to work to protect it).

If you take a bird's eye view of the ocean, you can see it is actually a palette of blue and green. The most important influence of the color variations are the phytoplankton drifting at the ocean surface. Phytoplankton (commonly known as algae) are to the ocean what grass and bushes and trees are to land - the biological foundation of life, due to their ability to convert sunlight into organic matter (they are also what cause waves to glow!!).

Phytoplankton are single-celled organisms that contain chlorophyll which allows them to carry out photosynthesis. Phytoplankton, along with microbes, share the bottom rung of the oceanic food ladder. Bacteria and viruses prey on phytoplankton, returning their nutrients to the sea as part of a very important microbial loop. At the same time, tiny animals graze on phytoplankton, and they are eaten by small fish or crustaceans, which are eaten by larger fish, whales, penguins, and everything else that swims in the ocean's salty waters. Were it not for phytoplankton, the world's largest animal, the blue whale, would not exist.

If we looked just a little closer at the oceans, then we would notice the coastlines, the irregular boundaries between land and sea. There are about 372,000 miles (620,000 kilometers) of coastline! For a reference, if you were to measure around the equator, it's only 24,901.46 miles... so basically coastlines measure the same as about 15 trips around Earth.

Another interesting fact... over one-third of the total human population, nearly 2.4 billion people, lives within 100 km (60 miles) of an oceanic coast. A fact I was surprised to learn... maybe because I grew up about 8 times that distance from the nearest beach, and I lived in a coastal state...

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