The largest known meteorological flood—one caused by rainfall, as in the current Mississippi River flood—happened in 1953, when the Amazon River overflowed.

The water is saltwater but less salty than the ocean. During the last ice age, the Black Sea was a freshwater lake.

With rivers providing an abundant supply of fresh water, the upper layers of the Black Sea are less dense than its saltier lower layers. Furthermore, a high concentration of hydrogen sulfide, an extremely toxic gas, lies dormant in the deepest layers of the Black Sea.

The Turkish Straits connect the Black Sea with the Aegean Sea and comprise the Bosporus, the Sea of Marmara, and the Dardanelles….

the Red Sea

A long time ago, whether your time frame is biblical or geological, the Black Sea was a large freshwater Black “Lake.” It was cut off from the Mediterranean Sea by a high piece of land that dammed the entry of salty seawater through the narrow connecting Bosphorus valley.

During the last of the great glaciations, the Black Sea became a large freshwater lake. The present connection to the Mediterranean Sea—and to salt water—is believed to have emerged some 6,500 to 7,500 years ago. Strong earthquakes—such as the Crimean earthquake of 1927—remain associated with the area.

Illegal fishing in the Black Sea is rapidly increasing, affecting both the marine biodiversity as well as economic activities in the region, in particular the fishing industry. The introduction of alien species, for example the rainbow comb jelly fish (Mnemiopsis leidyi), has severely affected the marine biodiversity.

(i) Red Sea – It is named Red sea because it contains a Cyanobacteria which turns the normally blue – green water a reddish one. It gets connected to the ocean without even one river meeting the sea. (ii) Black Sea – The Black Sea was first named by the ancient greeks as in hospitable sea.