Why do the water in the Pacific and Atlantic oceans have two different colors?

Many people think that the seas are a unified block and they are only divided into oceans to name them. But real oceans have vivid, unexpected boundaries.

If you go to the boundary between the Pacific and Atlantic Oceans, you will feel "Wow" because the natural phenomenon is so amazing. Accordingly, the water area between the two oceans has a clear dividing line. Looking from above, visitors can see two bodies of water that do not mix with each other and have different colors.

A series of videos on Youtube and TikTok have attracted a lot of views as they show a strange line splitting the middle of the ocean, with one side of the sea being dark while the other is lighter in color.

According to Live Science, such 'boundaries' often appear in areas where rivers flow into the sea, or near the shelves of glaciers floating in the ocean. However, in videos posted on social networks, the poster claims that the dividing line is the boundary between the Pacific and Atlantic Oceans, and asserts that this is 'proof' that the water of the two oceans do not mix with each other.

Below the video, many viewers asked different questions. Does that strange dividing line really exist? Do the waters of the Pacific and Atlantic Oceans mix, or is there a clear separation?

According to Nadín Ramírez, an oceanographer at the University of Concepción in Chile, the answer is yes, as bodies of water constantly mix with each other. Accordingly, Pacific and Atlantic ocean waters mix at different rates in different places, while climate change has a certain impact on this rate.

Imagine pouring instant cream into a cup of coffee. The liquids will mix together, but at a gradual pace. The same thing happens in videos or images showing the boundaries between different ocean waters. Because the ocean water on one side may be saltier, cleaner or colder, these differences take time to neutralize.

Of course, the neutralization speed will be faster under the influence of strong winds and large waves. It's like using a spoon to vigorously stir a cup of coffee, causing the cream to dissolve faster in the cup.

Also according to scientists, the mixing speed of seawater from the Pacific and Atlantic Oceans will happen faster in some places than in others.

For example, the two oceans meet near the southern tip of South America, where a series of small islands gather. Between those islands, ocean currents move relatively slowly and the Strait of Magellan is a popular route for ships to pass through. In the Beagle Channel, water from melting glaciers creates lines between fresh and salt water, creating a scene that looks a bit like the sea lines in YouTube videos.

Notably, in the area where the Strait of Magellan joins the Atlantic Ocean, a separation line appears that is difficult to see with the naked eye, but oceanographers can detect it with measurements.

On the measurement chart, a blue strip of water appears in the Atlantic Ocean. Meanwhile, Pacific ocean water has a different color due to more rain and lower salinity. But this boundary line only exists at sea for a while, before being erased by storms and waves.

In some open areas between South America and Antarctica, such as the Drake Strait - where waves can be up to 18m high, the mixing of seawater from the two oceans is even stronger.

Seawater also mixes in the great depths of the ocean. Casimir de Lavergne, a researcher at Sorbonne University and the French National Center for Scientific Research (CNRS), said daily tides pull water back and forth on the rough seabed. That causes a lot of turbulence.

But seawater from different sources can also move around the ocean without much mixing. The ocean is like a cake with many different layers, but those layers are water. In the middle layer, away from both the surface and the seafloor, water mixes more slowly because there is less turbulence.

Ocean researchers also distinguish between mixing and exchange of seawater. Mixing means "irreversibly altered waters". Thanks to global ocean currents, the Pacific and Atlantic Oceans exchange water continuously.

A strong current around Antarctica's Southern Ocean pulls water clockwise through Drake Strait from the Pacific to the Atlantic. It also takes water from the world's ocean basins, and then pumps it back. Another ocean current moves water from the Pacific through the Indian Ocean and around the tip of South Africa to feed into the Atlantic from the other direction.

Water always mixes at the edges of these flows. But because the different layers don't mix completely, oceanographers can track different water masses as they move across the globe.

In general, the Pacific and Atlantic Oceans mix together, but it's not as simple as two bodies of water just mixing together. Differences in density, temperature and salinity between the two oceans create barriers that prevent their waters from mixing easily. However, there are some areas where the two oceans mix, such as Drake Strait and the Gulf of Mexico.