The ocean is salty because water carries minerals from rocks into the sea

[00:00:00]Ever wondered why the ocean tastes salty, but rivers and rain don't?

[00:00:05]The answer is a story millions of years in the making. It starts with rain.

[00:00:09]Rainwater is slightly acidic, and as it hits rocks on land, it slowly dissolves tiny bits of mineral, including sodium and chloride. Those minerals hitch a ride. Rivers wash them downhill, draining into the sea drop by drop, year after year. Here's the trick. The sun evaporates the water back into clouds, but the salt is too heavy to rise. So, it stays and stays and stays. There's a second source, too. Hydrothermal vents on the seafloor, where hot water pushes even more dissolved minerals straight into the deep. Multiply this by billions of years, and the ocean becomes a giant salty soup, about 3 and 1/2% salt by weight. So, next time you taste the sea, remember, it's rain, rocks, and time slowly seasoning the planet's biggest bowl of water.