The Mediterranean Sea refers to the vast body of water between Asia, Africa and Europe. It is the largest intercontinental sea in the world. It is about 4,000 kilometers long from east to west, 1,800 kilometers wide from north to south, and covers an area of ??more than 2.5 million square kilometers. Bounded by the Tunis Strait between the Apennine Peninsula, Sicily and Tunisia, it is divided into east and west parts. The average depth is 1,450 meters and the deepest is 5,092 meters. The salinity is relatively high, up to 39.5‰. The earliest Jews and ancient Greeks simply called it "the sea" or "the sea". Because ancient people only knew that this sea was located between three continents, it was called the "Mediterranean Sea". The spellings in English, French, Spanish, Portuguese and Italian come from the Latin Mare Mediterraneum, where "medi" means "between", "terra" means "land", and the full name means "the sea in the middle of the land". The name first appeared in ancient books in the 3rd century AD. In the 7th century AD, the Spanish writer Isil first used the Mediterranean as a geographical name. The three major peninsulas of Southern Europe and islands such as Sicily, Sardinia, and Corsica divide the Mediterranean Sea into several small sea areas: Ligurian Sea, Tyrrhenian Sea, Adriatic Sea, Ioni Asia Sea, Aegean Sea, etc. The Mediterranean Sea occupies an important position both in transportation and strategy. It leads to the Atlantic Ocean via the Strait of Gibraltar to the west, the Black Sea via the Turkish Strait to the northeast, and the Red Sea to the Indian Ocean via the Suez Canal to the southeast. It is an important waterway between Europe, Asia and Africa, and an important channel for communication between the Atlantic Ocean and the Indian Ocean. Important seaports along the coast include Gibraltar (UK), Marseille (France), Genoa, Naples (Italy), Split, Rijeka (Croatia), Durres (Albania), Algiers (Algeria), Port Said (Egypt) etc. Although there are many rivers flowing into the Mediterranean, such as the Nile, Rhone, Ebro, etc., because it is in the subtropics, evaporation is too large, far exceeding the supply of river water and rainwater, making the water revenue of the Mediterranean less than the expenditure. The salinity of seawater is much higher than that of the Atlantic Ocean. Water from the Atlantic Ocean flows into the Mediterranean Sea from the upper layer of the Strait of Gibraltar. The high salt water from the Mediterranean Sea flows from the lower layer of the Strait like the Atlantic Ocean. The Atlantic Ocean is large and has sufficient water. The net flow of water into the Mediterranean Sea is a lot, as much as 7,000 cubic meters per second. Without the steady supply of water from the Atlantic Ocean, in about 1,000 years the Mediterranean Sea would dry up and turn into a giant salty depression. The Mediterranean Sea is surrounded by the European continent to the north, the African continent to the south, and the Asian continent to the east. It is about 4,000 kilometers long from east to west and about 1,800 kilometers at its widest point from north to south. It covers an area of ??2.516 million square kilometers. It is the largest intercontinental sea in the world. The Mediterranean Sea is connected to the Atlantic Ocean in the west through the Strait of Gibraltar, and to the Black Sea in the east through the Turkish Straits (Dardanelles, Bosporus, Sea of ??Marmara). The Suez Canal, opened in the 19th century, connected the Mediterranean and the Red Sea. The Mediterranean Sea is the oldest sea in the world, older than the Atlantic Ocean. The Mediterranean Sea is located at the junction of the Eurasian continent and the African continent, and is one of the strongest earthquake zones in the world. In the Mediterranean region there are Mount Vesuvius and Mount Etna. As an intercontinental sea, the Mediterranean Sea is relatively calm. With its winding coastline and numerous islands, it has many natural and good ports, making it an important transportation artery connecting the three continents. Such conditions have made maritime trade prosperous in the Mediterranean since ancient times, and became the cradle of ancient Egyptian civilization, ancient Greek civilization, and the Roman Empire. It is now also one of the important locations for maritime traffic in the world. The Phoenicians, Cretans, Greeks, and later the Portuguese and Spanish were all peoples with advanced navigation industries. Famous navigators such as Columbus, Vasco da Gama, Magellan, etc. all came from countries along the Mediterranean Sea. The Mediterranean coast has hot and dry summers and warm and humid winters, which is called a Mediterranean climate. Because of this climate, olive trees and other types of trees mostly grow along the coast. The vegetation along the Mediterranean coast is dominated by evergreen shrubs, with hard leaves, waxy leaves, deep roots, and drought tolerance to adapt to the hot and dry climate in summer. This is Europe's main subtropical fruit-producing area, rich in citrus, figs, grapes, etc., as well as the woody oil crop olives. The Mediterranean Sea is also the largest intercontinental sea (inland sea) in the world and the dirtiest sea in the world.