Adriatic Sea
The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto to the northwest and the Po Valley. The countries with coasts on the Adriatic are Albania, Bosnia and Herzegovina, Croatia, Italy, Montenegro, and Slovenia.
The Adriatic contains more than 1,300 islands, mostly located along its eastern coast. It is divided into three basins, the northern being the shallowest and the southern being the deepest, with a maximum depth of. The prevailing currents flow counterclockwise from the Strait of Otranto. Tidal movements in the Adriatic are slight, although larger amplitudes occur occasionally. The Adriatic's salinity is lower than the Mediterranean's because it collects a third of the fresh water flowing into the Mediterranean, acting as a dilution basin. The surface water temperatures generally range from in summer to in winter, significantly moderating the Adriatic Basin's climate. The Adriatic Sea sits on the Apulian or Adriatic Microplate. In the Late Oligocene, the Italian Peninsula first formed, separating the Adriatic Basin from the rest of the Mediterranean. The western coast is alluvial or terraced, while the eastern coast is highly indented with pronounced karstification. There are dozens of marine protected areas in the Adriatic, designed to protect the sea's habitats and biodiversity—more than 7,000 species are identified as native to the Adriatic, many of them endemic, rare and threatened ones.
The Adriatic's shores are populated by more than 3.5 million people; the largest cities are Bari, Venice, Trieste and Split. Early settlements on the Adriatic shores were Etruscan, Illyrian, and Greek. By the 2nd century BC, the region was under Rome's control. In the Middle Ages, the sea was controlled, to a varying extent, by a series of states—most notably the Byzantine Empire, the Croatian Kingdom, the Republic of Venice, the Habsburg monarchy and the Ottoman Empire. The Napoleonic Wars resulted in the Austrian Empire gaining control of most of the eastern Adriatic shore and the Po Valley, while the Kingdom of Italy gradually took control of the remaining Italian coast during the 19th century. Following the collapse of Austria-Hungary in 1918, control of the eastern coast passed to Yugoslavia and Albania, which agreed on their maritime boundaries with Italy in 1975 and 1992 respectively. After Yugoslavia's dissolution during the 1990s, its four coastal successor states—Slovenia, Croatia, Bosnia and Herzegovina, and Montenegro—continued to recognise the previous maritime border with Italy, but have disputed the borders between themselves.
Fisheries and tourism are significant sources of income along the Adriatic coast. Maritime transport is also a significant branch of the area's economy—there are 19 seaports in the Adriatic that each handle more than a million tonnes of cargo per year. The largest Adriatic seaport by annual cargo turnover is the Port of Trieste, while the Port of Split is the largest by passengers served per year.
Name
The origins of the name Adriatic are linked to the Etruscan settlement of Adria, which probably derives its name from Illyrian adur 'water, sea'. In classical antiquity, the sea was known as Mare Adriaticum or, less frequently, as Mare Superum ' upper sea'. The two terms were not synonymous, however. Mare Adriaticum generally corresponds to the Adriatic Sea's extent, spanning from the Gulf of Venice to the Strait of Otranto. That boundary became more consistently defined by Roman authorsearly Greek sources place the boundary between the Adriatic and Ionian seas at various places ranging from adjacent to the Gulf of Venice to the southern tip of the Peloponnese, eastern shores of Sicily and western shores of Crete. Mare Superum on the other hand normally encompassed both the modern Adriatic Sea and the sea off the Apennine peninsula's southern coast, as far as the Strait of Sicily. Another name used in the period was Mare Dalmaticum, applied to waters off the coast of Dalmatia or Illyricum. During the early modern period, the entire sea was also known as the Gulf of Venice, although that name is now informally applied only to the northern area of the sea, from Maestra Point in the Po Delta to Cape Kamenjak on the Istrian Peninsula.The names for the sea in the languages of the surrounding countries include ; ; ; ; ; ;, Јадранско море; ;. In Serbo-Croatian and Slovene, the sea is often referred to as simply Jadran.
Geography
The Adriatic Sea is a semi-enclosed sea, bordered in the southwest by the Apennine or Italian Peninsula, in the northwest by the Italian regions of Veneto and Friuli-Venezia Giulia, and in the northeast by Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, and Albania—the Balkan peninsula. In the southeast, the Adriatic Sea connects to the Ionian Sea at the wide Strait of Otranto. The International Hydrographic Organization defines the boundary between the Adriatic and the Ionian seas as a line running from the Butrinto River's mouth in Albania to the Karagol Cape in Corfu, through this island to the Kephali Cape, and on to the Santa Maria di Leuca Cape. It extends from the northwest to the southeast and is wide. It covers and has a volume of. The Adriatic extends northwest from 40° to 45°47' north, representing the Mediterranean's northernmost portion. The sea is geographically divided into the Northern Adriatic, Central Adriatic, and Southern Adriatic.The Adriatic Sea drainage basin encompasses, yielding a land–sea ratio of 1.8. The drainage basin's mean elevation is above sea level, with a mean slope of 12.1°. Major rivers discharging into the Adriatic include the Po, Soča, Krka, Neretva, Drin, Buna, and Vjosë. In the late 19th century, Austria-Hungary established a geodetic network with an elevation benchmark using the average Adriatic Sea level at the Sartorio pier in Trieste, Italy. The benchmark was subsequently retained by Austria, adopted by Yugoslavia, and retained by the states that emerged after its dissolution. In 2016, Slovenia adopted a new elevation benchmark referring to the upgraded tide gauge station in the coastal town of Koper.
The Alps, which also have a large meteorological impact on the Mediterranean, touch the Adriatic in the area around Trieste towards Duino and Barcola.
File:Bucht von Kotor.jpg|thumb|right|Bay of Kotor, a ria in the Southern Adriatic|alt=Looping river
Exclusive economic zone
in Adriatic Sea:| Number | Country | Area |
| 1 | ' | 63,600 |
| 2 | ' | 55,961 |
| 3 | ' | 11,105 |
| 4 | ' | 7,460 |
| 5 | ' | 192 |
| 6 | ' | 50 |
| Total | Adriatic Sea | 138,600 |
Bathymetry
The Adriatic Sea's average depth is, and its maximum depth is ; however, the North Adriatic basin rarely exceeds a depth of. The North Adriatic basin, extending between Venice and Trieste towards a line connecting Ancona and Zadar, is only deep at its northwestern end; it gradually deepens towards the southeast. It is the largest Mediterranean shelf and is simultaneously a dilution basin and a site of bottom water formation. The Middle Adriatic basin is south of the Ancona–Zadar line, with the deep Middle Adriatic Pit. The deep Palagruža Sill is south of the Middle Adriatic Pit, separating it from the deep South Adriatic Pit and the Middle Adriatic basin from the South Adriatic Basin. Further on to the south, the sea floor rises to to form the Otranto Sill at the boundary to the Ionian Sea. The South Adriatic Basin is similar in many respects to the Northern Ionian Sea, to which it is connected. Transversely, the Adriatic Sea is also asymmetric: the Apennine peninsular coast is relatively smooth with very few islands and the Mount Conero and Gargano promontories as the only significant protrusions into the sea; in contrast, the Balkan peninsular coast is rugged with numerous islands, especially in Croatia. The coast's ruggedness is exacerbated by the Dinaric Alps' proximity to the coast, in contrast to the opposite coast where the Apennine Mountains are further away from the shoreline.Hydrology
The coastal water dynamics are determined by the asymmetric coasts and the inflow of the Mediterranean seawater through the Straits of Otranto and further on along the eastern coast. The smooth Italian coast allows the Western Adriatic Current, which is composed of the relatively freshwater mass on the surface and the cold and dense water mass at the bottom, to flow smoothly. The coastal currents on the opposite shore are far more complex owing to the jagged shoreline, several large islands and the proximity of the Dinaric Alps to the shore. The last produces significant temperature variations between the sea and the hinterland, which leads to the creation of local jets. The tidal movement is normally slight, usually remaining below. The amphidromic point is at the mid-width east of Ancona.The normal tide levels are known to increase significantly in a conducive environment, leading to coastal flooding; this phenomenon is most famously known in Italy—especially Venice—as acqua alta. Such tides can exceed normal levels by more than, with the highest tide level of observed on 4 November 1966. Such flooding is caused by a combination of factors, including the alignment of the Sun and Moon, meteorological factors such as sirocco related storm surges, and the basin's geometric shape. Moreover, the Adriatic's long and narrow rectangular shape is the source of an oscillating water motion along the basin's minor axis. Finally, Venice is increasingly vulnerable to flooding due to coastal area soil subsidence. Such unusually high tides resulting in flooding have also been observed elsewhere in the Adriatic Sea, and have been recorded in recent years in the towns of Koper, Zadar and Šibenik as well.
File:Vrulja kod Omiša.jpg|thumb|right|A submarine spring near Omiš, observed through sea surface rippling
It is estimated that the Adriatic's entire volume is exchanged through the Strait of Otranto in 3.4±0.4 years, a comparatively short period. This short period is particularly important as the rivers flowing into the Adriatic discharge up to. This rate of discharge amounts to 0.5% of the total Adriatic Sea volume, or a layer of water each year. The greatest portion of the discharge from any single river comes from the Po, with an average discharge from it alone of. In terms of the annual total discharge into the entire Mediterranean Sea, the Po is ranked second, followed by the Neretva and Drin, which rank as third and fourth. Another significant contributor of freshwater to the Adriatic is the submarine groundwater discharge through submarine springs ; it is estimated to comprise 29% of the total water flux into the Adriatic. The submarine springs include thermal springs, discovered offshore near the town of Izola. The thermal spring water is rich with hydrogen sulfide, has a temperature of, and has enabled the development of specific ecosystems. The inflow of freshwater, representing a third of the freshwater volume flowing into the Mediterranean, makes the Adriatic a dilution basin for the Mediterranean Sea. The Middle and South Adriatic Gyres, are significant cyclonic circulation features, with the former being intermittent and the latter permanent. The SAG measures in diameter. It contributes to the flow of bottom water from the Adriatic to the Levantine Basin through the Ionian Sea. Through that process, the Adriatic Sea produces most of the East Mediterranean deep water.