Why don't the Pacific and Atlantic Oceans mix?

If you were to go into space right now and look down at the Earth, you would see two distinct things. You would see the land via the continents that we live on, but you would also go and see the oceans that fill the planet with the water we depend on. And from that distance you would think that all the oceans seamlessly blend into one another in such a way you'd think it was a grand design. But, when you get closer and close to those said waters, you'll notice that there are clear differences in the looks of those oceans. Specifically, the Pacific and the Atlantic Oceans. They honestly don't mix, and it's caused a lot of people a lot of confusion as to why that is. Because on the surface (pun intended), it doesn't make sense that they wouldn't mix. Because both are water, and they obviously have some balance in order to "live" next to one another, so why is it that they don't mix like they should?

If you go to certain areas of the world, you'll be able to see actual borders of the oceans colliding with one another in a way that makes it clear that you're looking at two very different bodies of water. But what exactly is going on here? How is it possible that two bodies of water cannot mix in this way and look so different? This is because of a very basic factor about water. Mainly, its salinity. Salinity is literally about the amount of salt that is dissolved within a body of water. That's why oceans are known as saltwater and rivers for the most part is freshwater because they don't have as much salt in them and thus are safe to drink. Because of the different locations, temperatures, weather patterns, lifeforms and more that lie within and around the various oceans, the salinity of each is different. And since they are so different, they cannot mix. This results in areas of the world where the oceans meet in such a way that they literally cannot mix and you can see key differences between them. And there are multiple places like this all over the world. A fun fact about this is that legendary ocean documentary maker Jacques Cousteau was the person to discover this border between the two oceans.

These Haloclines or "Ocean Clines" are the clearest way of noticing that the oceans for one reason or another aren't mixing, and they've created several myths about was truly going on because of the fact that this was "so spectacular" and "so weird". But you might be wondering, "Just how salty does it have to be to make one of these Haloclines?" Well, as noted, it has to do with Salinity, but to be more specific, you have to make it so that the water is at least 5 times saltier than the ocean that it is clashing up against. If you want to test this out for yourself, you can do it very easily if you're in the right spot. All you have to do is get some sea water or ocean water, and then our that into a glass about halfway. Then, get some fresh water from your tap or a local river and then fill the rest of the glass. You'll see immediately that these waters don't mix, and that dividing line in the middle is the Halocline.

A key difference though is that the Halocline you'll see in the glass in horizontal. because of how gravity and the Earth is oriented, the ones in the oceans are actually vertical. Though when you see it from your perspective on the top of the ocean, they'll seem horizontal. But if you were to dive into the oceans (like Jacques Cousteau did when he discovered them), you'll see that they indeed go up and down. Now at this point you might be thinking, "Well wait a minute, if the salinity is messing with the water, and it's great enough, shouldn't it be denser? And thus, shouldn't the denser water be below the less dense water?" If this was basic forces at work here, you would be right. 9/10 a denser object will sink while a less dense object will float. And to an extent, the oceans do this, but not when it comes to the clash of oceans.

Mainly because when you compare the densities of the two oceans, they're honestly not that much different even with the various salinity. It does cause them not to mix along with the salt, but it's not enough of a shift in order to go up and down and "layer" each other. Ironically, if this was to happen, the Haloclines wouldn't be noticeable unless you dove down into the water itself. There's more going on here though than just density and salt though, there are also properties of Inertia at work here. Before we dive into the science of Inertia, be sure to like the video and subscribe to the channel! That way you don't miss any of our weekly videos! Anyway, getting back to the topic at hand here, Inertia is another force that leads to the Haloclines being formed. In this case, it's the property known as the Coriolis Force.

Let's go back out into space and look at the Earth. If you watch it for a good period of time, you'll see that it's moving, right? In fact, it's spinning in place, and it rotates once every 24 hours, and that's why we have a day. Now, because of this, the Coriolis Force is born, and that makes it so that various objects and entities on Earth are moving in both typical and atypical fashions because the Earth is moving, but also, because the Earth is moving slowly. To put it even more simply, in the Northern Hemisphere, things like the ocean move in a clockwise direction, but then, in the southern hemisphere, it moves in a counterclockwise motion.

So thus, when these two oceans meet at certain places, not only are they conflicting in their composition, they are conflicting in regards to how they are moving. These forces aren't going to mix because they are literally beating up against one another. This is an important thing to note because of one of the other reasons that the oceans don't mix, the strength of the connection between their molecules. While we may be made up of all sorts of things, everything boils down to molecules and what they can do. Even something as complex as humans, or as simple as water, has a bunch of molecules guiding them and keeping things together.

But every object and entity have different strengths in the connection of their molecules. In the case of the Pacific and Atlantic Oceans, their molecules have different tensile strengths because of their composition, salinity, etc. And when you add that to the Coriolis effect, you'll see very quickly that they can't mix because they honestly don't have time to. The differences in the rotations of these oceans cause the molecules to meet for only fractions of a second, and due to that, they don't have time to mix. If things slowed down, or the two oceans suddenly span in the same direction, yeah, it could work. But based on what they are like right now? It's not likely to happen, and thus the Haloclines exist. Based on everything you've seen and heard so far, you might think that this "not mixing" phenomena is only found in the oceans of the world, and you would be correct in certain places, but not in regards to the whole of the Earth.

If you knew where to look, you'd find that the rivers, seas, lakes, oceans, and more often times clash, and when they do, they often have their own Haloclines, and at times, it can be quite a beautiful thing to see because of the different colors that are going on with these bodies of water. But what if I told you that these aren't the only borders you can find in the oceans and waters of the world? There is also an event known as a Thermocline, and that sounds exactly as you think it would. Because this is about borders that occur due to the different temperatures that reside within the waters of the world. A great example of this is the Gulf Stream waters which are much warmer, versus the arctic waters which are obviously much colder. These can create borders themselves, and at times, they can be either vertical or horizontal in nature, it just depends on the spot. Yet another kind of divide that you can find in the waters of the world are known as Chemoclines.

These are divides that are caused even more by the chemical makeup and even the microbes that are found within these particular bodies of water. It's a very interesting thing to see. If you wanted to see this kind of divide for yourself, the best example would be that of the Sargasso Sea, and it's the most famous of this kind of divide. The irony is that it is a sea within an ocean. In this case, it's a sea within the Atlantic Ocean, and just as unique, it doesn't have any shores to speak of. "But how can we notice it then if it's not next to any shores?" You're thinking of it backwards, you can't not notice it because of its makeup, so it doesn't need shores to show its borders.

That's just how the cline works because that body of water clashes with the rest of the Atlantic Ocean around it, thus making a sea that is unique and visible despite it not being tied to anything but the spot it's in. If you want even more examples of the kind of clines you can find all over the world, you honestly don't have to look that hard or that far. For example, there is one "convergence" that happens off the coast of Denmark where the North Sea and the Baltic Sea meet. These two show a very distinct "line in the sand" that mystified people for a long time because it just looked so unnatural. When as we explained, it's very natural.

This is a case of a Halocline because of density and salinity in the waters. However, unlike many of the Haloclines we've outlined, these two honestly do mix at a point, and because of that, some of the salinity spills over. There have even been cases of these two making waves as they clash into one another, and a byproduct of that is foam! Keeping in the area, we now head to the Mediterranean Sea, and when it mixes with the Atlantic Ocean, you'll see yet another Halocline. They meet at the legendary strait of Gibraltar, and because of their major differences in salinity, they too don't mix, and it's very visible, especially because of the strait that they mix in. A very famous one can be found further south with the Caribbean Sea and the Atlantic Ocean. Despite being a thing that mixes in several points, if you head to the Antilles, you'll see something very odd. Mainly, you'll notice the ocean and sea waters being slightly different shades of blue, and you literally watch the waters go from north to south and change colors before your very eyes. It almost looks like an optical illusion, but it's not, it's the waters adapting to the different salinities and compositions that are literally just feet away.

There are other places in the Caribbean that this happens, making it a popular tourist attraction for those who aren't familiar with the phenomenon. Sticking with the Atlantic, we move to the part of the ocean where it mixes with the Surinam River. These two forces meet in South America near Paramaribo. And when you go there, you'll notice the Halocline very easily. Or how about the Uruguay River and its afflux? This is literally one body of water, but it's separated because of the differences between it. One section of the river is used for freshwater for farmers and agriculture, while the other is loaded with other components, and even turns red at times because of its composition. It even makes it look like the water is "poisoned" while the other side is perfectly clean. The more you look around the world, the more you're going to see haloclines, thermoclines, chemoclines, and more.

There are even places where it's three different bodies of water or types of water mixing to create a Halocline of some kind. Some are even known to have much blacker colors while others are much lighter. All this goes to show that the waters of the world are so much more complex and unique than we give them credit for. We often say that all water is the same, or that it's freshwater or saltwater. But that's just an oversimplification of it all. Not to mention that it's wrong because we know that the waters of the world are all special, and that's why we need to take care of them. Seeing these borders and the differences between these oceans is further proof of that. And while they were once unexplained phenomena, now we can look at them and learn more about the oceans, seas, rivers, and more.