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What is Black Sea?

Looking for some Black Sea facts? Before we tell you some facts, let’s quickly answer this question – ‘what is Black Sea?’

It is an inland see located between Asia Minor and Southeastern Europe.

There are different hypotheses that try to explain its name, but no one has a definitive answer.

Black Sea is the world’s largest Meromictic Basin.

Now that you have a quick understanding of what is Black Sea and where it is located, let’s jump straight into the Black Sea facts.

Are you ready?

Of course you are!

In this list of Black Sea facts, we are going to answer the following questions:

  • Why is Black Sea called Black Sea?
  • Is Black Sea salt water or fresh?
  • Is Black Sea toxic?
  • Does Black Sea support life?
  • What are the different animal species we find in Black Sea?
  • Why do the organic matter that sink in Black Sea stay preserved?
  • Biblical importance (if any).
  • What are the different names of Black Sea?

Black Sea Facts: 1-5 | Why is it called Black Sea?

1. To start with, ‘Why is Black Sea called Black Sea?’ This is a very common question. Unfortunately, there’s no definitive answer. According to popular belief, Black Sea was once called as ‘Inhospitable Sea’ simply because it was difficult to navigate. Also, it was Inhospitable Sea because of some extremely ferocious tribes living at its shores.

2. The ancient Greeks however managed to colonize the sea shores and made it navigable. So, the name was changed to ‘Hospitable Sea’. But that doesn’t explain why the name ‘Black Sea’?

3. According to Smithsonian Science Education Center, there are two hypotheses for such a name. They are:

  • During winter months, severe storms over the Black Sea make the water appear Black to the sailors and hence the name – Black Sea.
  • The other hypothesis is that objects that drown in the Black Sea (such as metal objects from ships, animal matter or dead plant matter) and sink all the way down to 150 meters or more and stay there for quite some time, get a black sludge covering because of high hydrogen sulfide concentration. This is the reason why it is called Black Sea.

4. Here is another explanation. In the ancient times, directions were denoted by colors. The North was Black. The South was Red. The West was White. The East was Light Blue or Green. So, the Black Sea possibly simply meant – the Sea in the North.

5. But, the name Black Sea (Sea in the North) could only be given by those people who lived to the south of the Black Sea and to the north of the Red (that is South).

The Achaemenids (who lived between 550 BCE and 330 BCE) were the ones who were familiar with both the southern Red and the northern Black. Hence, Achaemenids were the one who probably gave the name Black Sea.

Black Sea Facts: 6-10 | Naming and Geography of Black Sea

6. There is yet another explanation for the name. During the winter times, a dense fog is developed over the Black Sea. It is so dense that it absorbs most of the sunlight that comes down on the sea, making it appear black, and hence the name.

One thing to note is that the density of this fog is so high that visibility in Black Sea is restricted to only 5 meters compared to Mediterranean Sea’s 35 meters of visibility.

7. Black Sea is an inland sea. It is sandwiched between Asia Minor and Southeastern Europe. The sea is surrounded by 6 countries. Those countries are: Georgia, Russia, Ukraine and Crimea, Romania, Bulgaria and Turkey.

8. This inland sea is connected with the Mediterranean Sea by the Dardanelles, Sea of Marmara and Bosporus. The Sea of Azov is the Black Sea’s largest arm and is connected to the Black Sea through Kerch Strait.

9. From East to West, the Black Sea runs 1,210 kilometers or 750 miles and is 560 kilometers or 360 miles wide. The maximum depth of the sea is at 2,245 meters or 7,364 feet.

10. Danube, Dniester, Southern Buh and Dnieper are the primary rivers that feed the Black Sea with fresh water.

Black Sea Facts: 11-15 | Physical Characteristics of Black Sea

11. Black Sea is world’s largest Meromictic Basin. Wait, what? Well, that simply means that upper water layer of the sea doesn’t mix with the deep water layer of the sea.

12. This nature of the Black Sea makes 90% or more of its deep water to be extremely anoxic (devoid of dissolved oxygen). The upper layer of water however is oxygenated and receives oxygen from atmosphere.

13. The only other water body with which the Black Sea exchanges water is the Mediterranean Sea. This water exchange takes place only through Dardanelles and Bosporus – both of which are very narrow and very shallow.

14. This has deep significance. The much more saline water from Mediterranean enters the Black Sea. The inflowing water has far more density than the outflowing water.

15. The outflowing water (that is the fresh water from Black Sea flowing out) lands in Sea of Marmara. The outflow happens at surface level while the inflow happens at the bottom.

Black Sea Facts: 16-20 | Physical Characteristics of Black Sea

16. This type of water exchange is classic estuarine circulation (denser saline water flows in at bottom but lighter and less saline water flows out at surface level).

17. One thing of note here is that the total inflow of freshwater into Black Sea from the rivers ensures that the outflow volume from Black Sea into Mediterranean is two times more that the inflow volume into Black Sea from Mediterranean.

18. Here is another interesting Black Sea fact. Dardanelles and Bosporus are shallow and narrow and hence, inflow and outflow have high speed currents. The vertical sheer is high and the two water layers mix turbulently in the Dardanelles and Bosporus.

19. Because of this turbulent mixing, the salinity of freshwater flowing out of Black Sea reaches 34 psu from 17 psu by the time the water reaches Mediterranean Sea. On the other hand, the saline water that flows into the Black Sea, loses its salinity from 38.5 psu to 34 psu. [PSU is particle salinity unit].

20. High tides and low tides are totally absent in Black Sea. This means that the sea level doesn’t fluctuate. This makes the sea a very calm and quiet sea.

Black Sea Facts: 21-25

21. Is Black Sea Toxic? The answer to this question is a bit complicated. The answer is both YES and NO. Modeling of the sea has shown that at the depths of 180 meters and beyond, where you find the high saline water, there is hydrogen sulfide. Yes, that is toxic and that is the reason why, marine lives do not exist at that depth.

22. In shallower depths, that is above 180 meters, there is no hydrogen sulfide and this is where all the marine life forms thrive in Black Sea.

23. Also, the reason why life cannot thrive in greater depths of the sea is that the water is anoxic. We discussed this in our previous article. It is worth reading. Go through it.

24. Can you swim in Black Sea? Don’t worry! It is not going to bite you. As we mentioned, it only gets toxic if you happen to reach the depths of the Black Sea. You really can’t swim all the way down to 180 meters, can you? And remember, there’s life in the top layer of water. So, if they can thrive, you can swim!

25. Here is a brilliant and really surprising Black Sea fact: Organic matter and anthropogenic artifacts like boat hull that sink all the way down to the depths of Black Sea, stay preserved.

The reason is simple! For them to decompose, there has to be oxygen that can be used by microbes. The water down below is anoxic (devoid of dissolved oxygen) and hence, such matter don’t decompose.

Black Sea Facts: 26-30

26. Did we mention why the water at such depths is anoxic? Well, it is not that organic matter (that sink in Black Sea) do not decompose or decay at all. They do but, at a very slow rate and whatever oxygen is there is used up, making the water anoxic. This further slows down decaying of organic matter and hence, we see well-preserved organic matter and anthropogenic artifacts.

27. Deep sea expeditions in Black Sea have turned some well-preserved ancient artifacts like Byzantine shipwreck, boat hulls, settlement remains and more. No wonder, Black Sea has received some attention from marine archaeologists.

28. Actually, quite large amounts of organic matter reach the bottom of Black Sea and they get accumulated in sediments. The concentration of organic matter in sediments at the bottom of Black Sea is a whopping 20%. These kinds of sediments actually have a name. They are called sapropel.

29. Talking of Hydrogen Sulfide, where does it come from? We said that at the depths of 180 meters and beyond (that is 600 feet and beyond), there is no oxygen or very little oxygen. Nothing lives there.

BUT we didn’t mention that there are some extremophile microorganisms down there. These microbes make use of sulfate and oxidize organic material. In the process, they end up producing Hydrogen Sulfide (H2S) and Carbon Dioxide (CO2) as byproducts. This is how Hydrogen Sulfide is formed in Black Sea.

30. Scientists have something interesting to say about the Hydrogen Sulfide. In case, the scientists say, an asteroid lands in Black Sea, it can cause serious problems. The Hydrogen Sulfide will be released in form of clouds and it can threaten the life of people and animals that live around Black Sea.

Black Sea Facts: 31-35

31. About Black Sea’s Biblical importance, we will like to start by saying that we are devout Hindus and we don’t believe in any other religion. Having said that, here is what people say – Black Sea is the point where Noah’s Ark finally rested. As the story goes (without any scientific base), Noah’s Ark landed on a high point after sailing for months. That high point is supposed to be Mount Ararat.

32. It happens that Mount Ararat is standing along coastline of Black Sea in Eastern Turkey. So, That’s the Biblical significance of Black Sea.

33. Coming to marine ecosystem of Black Sea, you will be surprised to know that despite there being almost no life in Black Sea beyond 180 meters of depth, the top layer of water of the sea is teeming with life. The first major being the Phytoplankton.

34. There are several groups of Phytoplankton present in Black Sea and those groups are:

  • Dinoflagellates – anywhere between 193 to 267 different species live there
  • Diatoms – several species live in the sea in form of colonies of heterotrophic, non-motile and unicellular algae.
  • Coccolithopores – these are autotrophic and motile Phytoplankton which produce coccoliths or CaCO3 plates. Emiliania huxleyi is the major species.
  • Cyanobacteria – these are the bacteria that get energy from photosynthesis.

35. If you really want to meet the wide array of marine life in Black Sea, start at the surfline and take a close look at the shallow sandy bottom. You will be greeted by benthic fish, molluscs and crabs, hiding themselves like champion camouflagers.

Black Sea Facts: 36-40

36. Comb a little more and you will be sure to find pipefish, stargazer, golden-grey and red mullets, flatfish and gobies.

37. For enhanced variety try diving into the rocky bottom habitats where sea anemones, shrimps and variedly bright blennies are aplenty. And yes, the sight of multicolored macroalgae is just breathtaking.

38. Knee-deep and all the way down to 15 meters and you will find little crustaceans, marine worms and miniature marine snails. And yes, there’s stone crabs – big ones and red triplefin are the tricky ones – always hiding from plain sight.

39. Those that aren’t shy at this depth are mullets and horse mackerels that sweep around in schools right over the brown algae jungle that you find there.

40. Black Sea is also home to a various jellyfish, scorpion fish, skates, common stingray, piked dogfish (a shark actually), seahorse, goat fish, hermit crab, blue sponge, common dolphin and bottle nose dolphin, harbor porpoise etc.

Different Names of Black Sea

It shouldn’t come as a surprise that the Black Sea is known by several names because it is surrounded by 6 different countries. Each country has its own unique name. The name given to Black Sea in each country is given in the table below:

CountryName of Black Sea
RussiaChornoye More
UkraineChorne More
BulgariaCherno More
TurkeyKara Deniz
GeorgiaShavi Zghva
RomaniaMarea Neagra


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