In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end of the Balkan Mountains; and the Dobruja Plateau considerably farther north.

[5] Important cities along the coast include (clockwise from the Bosporus) Burgas, Varna, Constanța, Odesa, Sevastopol, Novorossiysk, Sochi, Poti, Batumi, Trabzon and Samsun.

Some scholars understand the name to be derived from a system of color symbolism representing the cardinal directions, with black or dark for north, red for south, white for west, and green or light blue for east.

[33] While the exact mechanisms causing the North Atlantic Oscillation remain unclear,[34] it is thought the climate conditions established in western Europe mediate the heat and precipitation fluxes reaching Central Europe and Eurasia, regulating the formation of winter cyclones, which are largely responsible for regional precipitation inputs[35] and influence Mediterranean sea surface temperatures (SSTs).

Seismic surveys indicate that rifting began in the Western Black Sea in the Barremian and Aptian followed by the formation of oceanic crust 20 million years later in the Santonian.

[39][40][41] Since its initiation, compressional tectonic environments led to subsidence in the basin, interspersed with extensional phases resulting in large-scale volcanism and numerous orogenies, causing the uplift of the Greater Caucasus, Pontides, southern Crimean Peninsula and Balkanides mountain ranges.

The Euxine abyssal plain in the center of the Black Sea reaches a maximum depth of 2,212 metres (7,257.22 feet) just south of Yalta on the Crimean Peninsula.

Of continental origin, the lower level on the shelf is mostly alluvial sands with pebbles, mixed with less common lacustrine silts and freshwater mollusc shells.

[49] The Black Sea's circulation patterns are primarily controlled by basin topography and fluvial inputs, which result in a strongly stratified vertical structure.

As with all marine food webs, the Black Sea features a range of trophic groups, with autotrophic algae, including diatoms and dinoflagellates, acting as primary producers.

[59] During winter, strong wind promotes convective overturning and upwelling of nutrients, while high summer temperatures result in a marked vertical stratification and a warm, shallow mixed layer.

Since the 1960s, rapid industrial expansion along the Black Sea coastline and the construction of a major dam on the Danube have significantly increased annual variability in the N:P:Si ratio in the basin.

Additionally, an alien species—the warty comb jelly (Mnemiopsis leidyi)—established itself in the basin, exploding from a few individuals to an estimated biomass of one billion metric tons.

[86] The change in species composition in Black Sea waters also has consequences for hydrochemistry, as calcium-producing coccolithophores influence salinity and pH, although these ramifications have yet[when?]

[citation needed] Pollution-reduction and regulation efforts led to a partial recovery of the Black Sea ecosystem during the 1990s, and an EU monitoring exercise, 'EROS21', revealed decreased nitrogen and phosphorus values relative to the 1989 peak.

scientists have noted signs of ecological recovery, in part due to the construction of new sewage-treatment plants in Slovakia, Hungary, Romania, and Bulgaria in connection with those countries' membership of the European Union.

There are also catastrophic scenarios, such as the "Black Sea deluge hypothesis" put forward by William Ryan, Walter Pitman and Petko Dimitrov.

[90][91] The Black Sea was sailed by Hittites, Carians, Colchians, Armenians, Thracians, Greeks, Persians, Cimmerians, Scythians, Romans, Byzantines, Goths, Huns, Avars, Slavs, Varangians, Crusaders, Venetians, Genoese, Georgians, Bulgarians, Tatars and Ottomans.

The Black Sea became a virtual Ottoman Navy lake within five years of the Republic of Genoa losing control of the Crimean Peninsula in 1479, after which the only Western merchant vessels to sail its waters were those of Venice's old rival Ragusa.

Its site, on a deeply eroded, bare limestone promontory at the southwestern tip of the Crimea, made an approach by land forces exceedingly difficult.

The Soviet Navy had built upon these natural defenses by modernizing the port and installing heavy coastal batteries consisting of 180mm and 305mm re-purposed battleship guns which were capable of firing inland as well as out to sea.

[109][110] The Kalibr missile was so successful that on 10 March 2023 Defense Minister Sergey Shoigu announced plans to broaden the type of ship which carried it, to include the corvette Steregushchiy and the nuclear-powered cruiser Admiral Nakhimov.

[111] On the morning of 14 March 2023, a Russian Su-27 fighter jet intercepted and damaged an American MQ-9 Reaper drone, causing the latter to crash into the Black Sea.

At 13:20 on 5 May 2023 a Russian Su-35 fighter jet intercepted and threatened the safety of a Polish L-140 Turbolet on a routine Frontex patrol mission.. and performed 'aggressive and dangerous' manoeuvres.

[114] As of January 2025, neither Ukraine nor Russia control the Black Sea, making it contested, claims Estonian Navy Commander Ivo Värk.

Independent Ukraine continued and intensified that effort within its exclusive economic zone, inviting major international oil companies for exploration.

During this time sand shed off the rising Balkanide, Pontide and Caucasus mountains trapped organic material in the Maykop Suite of rocks through the Oligocene and early Miocene.

In 2010, Sinop-1 targeted carbonate reservoirs potentially charged from the nearby Maykop Suite on the Andrusov Ridge, but the well-struck only Cretaceous volcanic rocks.

A different Turkish well, Kastamonu-1 drilled in 2011 did successfully find thermogenic gas in Pliocene and Miocene shale-cored anticlines in the Western Black Sea.

In 2016, the Bulgarian well Polshkov-1 targeted Maykop Suite sandstones in the Polshkov High and Russia is in the process of drilling Jurassic carbonates on the Shatsky Ridge as of 2018.