Baku, Azerbaijan (Ports Europe) July 21, 2025 – Megalomaniac, absurd, or visionary — many terms could describe a proposal to build a tunnel linking the shrinking Caspian Sea to the Black Sea. The idea originates from Azerbaijan’s small Caspian port of Zira, located 45 km east of Baku, and the country’s ADO-G Group of Companies, a supplier of oil and mining equipment.
The official statement signed by the founder of ADO-G, Musa Suleymanov Samad, proposes the construction of an underground tunnel with a diameter of 10 meters. It will connect the Black Sea from the Georgian or Russian side with the Caspian Sea. Due to the 28-metre difference in elevation, water from the Black Sea would flow into the shrinking Caspian Sea without the need for pumps.
The idea is to stabilise the water level of the Caspian Sea, which is rapidly shrinking. This creates serious environmental, infrastructural and economic consequences for the littoral states. It is noted that an underground tunnel will meet all environmental requirements for the preservation of biodiversity.
If a project to build a tunnel linking the Caspian Sea with the Black Sea were to go ahead, the political implications would be extensive and contentious, with regional, environmental, and geopolitical dimensions.
Ideas for Caspian-Black Sea canals from 2007
In 2007, three options for connecting the Caspian Sea with the Black Sea were proposed and discussed during the International Scientific and Practical Conference: “Technosphere and Environmental Safety in Transport” in St. Petersburg.
- Construction of a second line of the Volga-Don Canal (VDSK) locks (with a possible connection to the Kuban River and an outlet to the Black Sea). VDSK connects the Volga and Don rivers at their closest points. Its length is 101 km, 45 km of which is through rivers and reservoirs. Together with the lower Volga and the lower Don, the canal provides the shortest navigable connection between the Caspian Sea and the Azov Sea (Black Sea).
- Construction of the EuroAsia Canal, which will also be used by vessels along the Kuma-Manych (Manycheskaya) Depression. It is a geological depression in southwestern Russia that separates the Russian Plain to the north from North Caucasus (Ciscaucasia) to the south and is named after Kuma and Manych rivers.
- Construction of the Kazak Canal along the Terek, Kuma and Kuban rivers. All three rivers are in Russia.
Background about the receding Caspian Sea
The shallowing trend of the Caspian Sea will continue in 2025, Vladimir Shevchenko, Acting Director of the state-controlled Institute of Oceanology of the Russian Academy of Sciences, said in June. He added that from 1977 to 1985, the Caspian Sea level was rising. However, since 1985, the sea level has been gradually decreasing.
Caspian Sea will continue to shrink in 2025 – scientists
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“The shallowing process of the Caspian Sea has been going on for many years,” Shevchenko said. “Since 1985, the water level in the sea has dropped by about three meters. This trend will continue this year, since the reason for the decrease is mainly due to the (negative) balance between the river inflow and the evaporation. In the context of climate change, accompanied by an increase in air temperature, the intensity of evaporation will continue to increase.”
The Caspian Sea is within weeks of reaching its lowest level on record, an Azerbaijani official said in December 2024, quoted by the Financial Times (FT) under the headline Caspian Sea on UN climate summit doorstep ebbs towards record low, as climate change causes lasting damage to the world’s largest inland body of water.
The Caspian Sea is the largest (371,000 to 384,400 km²) and most voluminous (78,000 to 78,700 km³) inland body of water in the world. Its physical environment and its floor have oceanic characteristics. The sea lies in an elongated depression between the European and Asian continental plates.
Its surface is well below sea level, with a maximum depth of 980 m in the south and a shallow northern half averaging just 5.2 metres. The sea extends more than 1,000 km from north to south. It is bounded by deserts in the north and east. Grasslands and forests enclose it in the west and south.
The surface of the world’s largest (salty) lake lying between Europe and Asia has fallen by several centimetres a year since the 1990s. The rate of water shrinkage is set to increase dramatically. This will happen as global temperatures continue to increase.
The Caspian’s low salinity is due to freshwater input. The giant Russia’s Volga River contributes up to 82% of the inflow, with the rest supplied by some 130 other rivers, principally the Ural, Kura and Atrek.
The Caspian Sea is also a key transport link in the Trans-Caspian International Transport Route (TITR, Middle Corridor) that bypasses Western sanctions-hit Russia and the promoted by Moscow International North-South Transport Corridor (INSTC) that bypasses sanctions. INSTC is also the conduit of Iranian military imports into Russia – drones and munitions arms.
The sea occupies a key location facilitating water transport in both North-South and East-West directions. Developing international rail transport also attracts more distant countries, such as India, to use the Caspian Sea as a route to states in Europe and Russia.
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Other similar overambitious projects
Greece-Serbia: A megalomanic project to construct a Danube River–Aegean Sea Canal has been a Serbian dream for well over a century. For several years, authorities in Belgrade have been talking about a Greek-Serbian proposal to be funded by China which is pharaonic – 651 km long river-based canal worth over $17 billion.
Analysis – Danube River–Aegean Sea Canal project surpasses the craziness of Kanal Istanbul
The anticipated Danube River–Aegean Sea Canal network would start from the port of Thessaloniki in Greece and end at the Danube River near Belgrade. Serbia is trying to position itself as an indispensable part of China’s Belt and Road Initiative’s penetration into the Balkans and Central Europe, radically changing the geopolitics of the region.
Bulgaria: A 50-year-old, overambitious project to connect Bulgaria’s largest Black Sea port of Varna and Ruse, the country’s biggest port on the Danube River, with a navigation canal received a positive vote in the transport committee of the European Parliament earlier in April 2023.
Over the years, the Communist era project has been talked about many times, and attempts have been made to resurrect it, but nothing real has ever come of it due to economic impracticality and lack of funds. Today, it appears that the canal can once again be on the agenda not only in Bulgaria, but also in the EU, and it has the opportunity to enter the Union’s priority transport network.
Surprisingly, the two ports are currently not linked with a railway line or a highway despite offering a unique opportunity for cargo transfer from the Black Sea to Central and Western Europe and back. A road and rail link will cost much less money and could be implemented faster, according to an article in the leading Bulgarian business weekly Capital.
Turkey: Companies with close ties to Turkish President Recep Tayyip Erdogan and the governing in Turkey Justice and Development Party (AKP), as well as Qatari senior officials and firms, could benefit the most from the $20 billion Kanal Istanbul project, linking the Black Sea and the Sea of Marmara (and the Mediterranean Sea), north and south of Istanbul, Sayari, a global corporate data provider and commercial intelligence platform, based in Washington, D.C. said in April 2020.
Ports Europe has extensive coverage of the controversial Kanal Istanbul project
The 45 km (nearly 28 miles) canal, an artificial sea-level waterway, will be built in Istanbul’s Kucukcekmece-Sazlidere-Durusu corridor. It is projected to have a capacity of 160 vessel transits a day – similar to the current volume of traffic through the parallel Bosphorus, where traffic congestion leaves ships queuing for days to transit the strait.
The new channel will not be subject to the international treaty, the Montreux Convention from 1936, that limits the access of warships to Black Sea. The Turkish strait is a natural passage, where ships have freedom of navigation. However, transit through the man-made Kanal Istanbul would be regulated by Turkey.
Kanal Istanbul bears the risks of highly affecting the surrounding ecosystem including the natural equilibrium of the Black and Mediterranean seas. If the project materialises, the balance will be reversed between the cold and fresh waters of the Black Sea and the warm and salty waters that come from the Mediterranean Sea. Adding a second tap between these seas will lead to Black Sea being emptied twice as fast with two taps while the flow rates and capacities of the rivers that feed the Black Sea stay the same.
