Why Is The Ocean Salty?

Jamie Hayes

Why Is the Ocean Salty?

The ocean is vast, unpredictable, and…salty. But why is the ocean salty? Rivers and lakes aren’t salty. The water in your tap isn’t salty (if you’re lucky). So why the ocean? Well, interestingly enough, the ocean actually wasn’t always salty—but a few billion years and some basic chemistry later, and we’re left with the saline seas we’ve got today. So how did it happen?

Ancient Oceans

When the Earth’s oceans first formed, it’s very likely that they were only a little salty. However, the water cycle of evaporation, clouds, and rain eventually changed all that. Soon enough, there were trillions of tons of salt in the ocean—and it all came from rocks on the land. But let’s back that up a bit more.

It might surprise you to know that rain isn’t pure water. It contains, among other things, dissolved carbon dioxide from our atmosphere. This forms carbonic acid and makes rainwater very slightly acidic. No, it won’t melt the clothes off your back, but it does mean that rainwater can dissolve minerals. Though it’s a slow process, the carbonic acid in rainwater will dissolve the rocks it passes over, picking up ions in the process. Among these ions are sodium and chloride—which make up, you guessed it, salt.

Something Doesn’t Add up

As the rainwater splashes on the rocks and ends up in the ocean, it deposits these salty ions. But wait, that doesn’t quite make sense, does it? Shouldn’t that mean that lakes and rivers would also be salty? Well, no. There certainly are mineral ions in rivers and lake water, but these ions tend to flow into the ocean and out of freshwater.

Plus, the ocean is very, very old, which has allowed a long time for salt to build up in it. But wait, there’s more! Eventually, thanks to various natural processes, this process of salt depositing has reached an equilibrium, which is why the ocean doesn’t keep getting saltier and saltier.

But Where’s all the Pepper?

So why is the ocean salty? We’ve just answered it! Before that balance was reached, however, a lot of salt was deposited in the ocean. In fact, it’s estimated that if you took all of the salt out of the ocean, it would cover the entire Earth’s land surface…in a layer that’s 500-feet thick. That’s a little salty for my tastes. I think I’ll leave it in the ocean, thank you.

Sources: 1, 2

Factinate Featured Logo Featured Article
When Edward VIII’s baby brother Prince John died of severe seizure at only 13 years old, Edward’s response was so disturbing it’s impossible to forget.
43 Scandalous Facts About Edward VIII, The King Who Lost His Crown 43 Scandalous Facts About Edward VIII, The King Who Lost His Crown “I wanted to be an up-to-date king. But I didn't have much time.”—King Edward VIII. For such a short-reigning king, Edward VIII left behind no shortage of controversy. First, there was the scandalous womanizing of…
Factinate Featured Logo Featured Article
The average person doesn't even get 50% correct. I guess it's hard to be smarter than an 8th grader...
Quiz: Are You Smarter Than An Eighth-Grader? Quiz: Are You Smarter Than An Eighth-Grader?
Factinate Featured Logo Featured Article
I had an imaginary friend named Charlie. My parents asked what he looked like, and I always replied “a little man.” When we moved away, Charlie didn't come with us. My mom asked where he was, and I told her that he was going to be a mannequin at Sears—but that wasn’t even the most disturbing part. The years passed by and I’d forgotten my imaginary friend, but when someone told me a story about my old house, I was chilled to the bone.
People Describe Creepy Imaginary Friends from Their Childhood People Describe Creepy Imaginary Friends from Their Childhood “I was a loner as a child. I had an imaginary friend—I didn't bother with him.”—George Carlin. Many adults had imaginary friends as children. At their best, these make-believe buddies were cute, helpful, and whimsical…
Factinate Featured Logo Featured Article
The average person only gets 10 right. You muggles don't stand a chance...
Quiz: How Much Do You Really Know About Harry Potter? Quiz: How Much Do You Really Know About Harry Potter?

Dear reader,

Want to tell us to write facts on a topic? We’re always looking for your input! Please reach out to us to let us know what you’re interested in reading. Your suggestions can be as general or specific as you like, from “Life” to “Compact Cars and Trucks” to “A Subspecies of Capybara Called Hydrochoerus Isthmius.” We’ll get our writers on it because we want to create articles on the topics you’re interested in. Please submit feedback to Thanks for your time!

Do you question the accuracy of a fact you just read? At Factinate, we’re dedicated to getting things right. Our credibility is the turbo-charged engine of our success. We want our readers to trust us. Our editors are instructed to fact check thoroughly, including finding at least three references for each fact. However, despite our best efforts, we sometimes miss the mark. When we do, we depend on our loyal, helpful readers to point out how we can do better. Please let us know if a fact we’ve published is inaccurate (or even if you just suspect it’s inaccurate) by reaching out to us at Thanks for your help!

Warmest regards,

The Factinate team