Today there are 63 seas on Earth. Most of them are connected to one or another ocean and only three are internal. Each sea has its own characteristics, including the purity and transparency of the water in it.
The first place in terms of water purity is occupied by the Dead Sea, which is located between Jordan and Israel. Its sterility is provided by a large amount of salt, which makes the water absolutely unsuitable for the existence of any living creatures - from fish to microorganisms. But this sea helps in the treatment of rheumatism and depression. Nevertheless, the purity of this object is under threat, because a person worsens the ecological situation every year.
The Weddell Sea, washing the shores of West Antarctica, is also one of the cleanest seas in the world. Almost 30 years ago, it was even entered into the Book of Records for this indicator. Studies conducted at that time showed that a special disk, which measures the transparency of water, was distinguishable at a depth of 79 meters out of 80 possible. Such indicators would hardly be possible if it were located near the places of residence of a person.
The inland sea of the Indian Ocean is not only the saltiest, but also one of the cleanest seas. Its area reaches 450 thousand square kilometers, and the volume of water in it is 251 thousand cubic meters. Also, the Red Sea is unmatched in the quantity and diversity of marine life. Its transparency is due to the absence of rivers flowing into it, which often carry sand and silt with them. Despite this, every year the ecological situation in the Red Sea is deteriorating, because some ships dump garbage and waste directly into the water.
The third place in terms of water purity is shared with the Red Mediterranean Sea. Near some of the coasts of Turkey and Greece, it even received the "Blue Flag" - a prestigious status indicating that the purity of the water meets the environmental requirements of the European Union. But on the coasts of France, Italy and Spain, the Mediterranean waters are considered rather dirty due to industrial waste that ends up in them. These countries have been fined more than once by representatives of the EU environmental organization.
The purity of the Aegean also depends on the coastline. Some of the most sterile waters wash around Greece, but off the coast of Turkey, the Aegean Sea systematically suffers from wastewater discharges. During the so-called "red tides", layers containing large amounts of nitrogen and phosphorus rise from the depths of this sea. Swimming in such water during this period, and even more so to consume seafood caught from it, is not recommended.