The Caspian sets in ambiguity. Mapmakers call it a sea, many hydrologists call it a lake, and Professor Anis H. Bajrektarević, in his works, prefers the term “water plateau,” a body of water that is neither. The question is more than semantic. Whether the Caspian is treated as a sea or as a lake determines who may fish, sail, drill, and build in it and under which rules. Lying between Europe and Asia, it binds together its five littoral countries: Russia, Iran, Azerbaijan, Kazakhstan, and Turkmenistan.
Two developments in 2026 show why the question has regained urgency. Regional scientists report that the sea has fallen to its lowest level in the instrumental record, and dredging is under way in Russian and Kazakh ports to keep them operational. At the same time, Iran, the only signer that has not yet ratified the 2018 Convention on the Legal Status of the Caspian Sea, approved the ratification bill in July and sent it to parliament after years of inaction.
Both stories point to the same problem: a shared system whose physical reality and legal framework are changing at different speeds. The Caspian is therefore a concrete test of the proposition at the centre of the Connectivity Doctrine of the Global Academy for Future Governance (GAFG): connectivity is produced less by infrastructure than by the coherence of the institutions that govern movement across it. This article moves from the Caspian’s
geography to its states, its legal status, its ecology, and its routes, and then asks what the Doctrine can add.
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A GEOGRAPHICAL CROSSROAD
The Caspian is the largest enclosed body of water on Earth; its morphological structure is diverse in various aspects: volume, depth, and salinity. These differences create traditional division into three distinct basins. The northern basin is a shallow shelf that never exceeds about 25 meters in depth, and it covers nearly a quarter of the surface. The central basin descends to almost 800 meters, while the southern basin is more than a kilometer. The Volga, Europe’s longest river, enters in the north and supplies most of the sea’s inflow, which makes the northern waters’ level fluctuations highly sensitive to any change in the river’s flow.
The river is also a fundamental connecting route, as it physically links the Russian north-south axis with the Caspian and with Iran and the Indian Ocean through the International North-South Transport Corridor (INSTC). Even if this junction exists, the latest sanctions and geopolitical rupture have fractured the activities and operations of the corridor. This proves how a physical link is not enough to provide functional connectivity without, at its base, a structured governance ecosystem.
The Caspian’s economy rests on fisheries, including sturgeon and caviar, on oil and gas, and on shipping. Shipping is the activity that most requires coordinated rules between the countries sharing the coastline, as the sea has no outlet to the ocean. Its only waterborne link to the global maritime network runs through the Volga and the Volga–Don Canal towards the Black Sea. While Russia and Iran have access to other seas, for Azerbaijan, Kazakhstan, and Turkmenistan, the Caspian is the only sea exposure they have, and reaching open water requires passage through neighboring territory.
FIVE LITTORAL STATES, FIVE STRATEGIES
The five littoral states—Iran and four post-Soviet states—share the same water but look at it from different strategic positions.
Russia treats the Caspian as part of its southern security environment and as a link in broader transport and trade networks, notably the INSTC.
Iran sees the basin as a strategic frontier and a possible bridge between Central Asia, the Caucasus, and the Persian Gulf, although sanctions and infrastructure gaps have limited its room for maneuver in recent years.
Azerbaijan has cast itself as a gateway between Central Asia and the South Caucasus, connecting Caspian resources and routes with markets further west.
Kazakhstan aims to diversify its exports and strengthen its westward links, in particular through the Trans-Caspian route.
Turkmenistan, endowed with large natural-gas reserves, is also seeking wider export options and better connections across the sea.
These interests overlap, but they do not automatically converge. Energy competition, security concerns, external partnerships, and disputes over resource development can all hinder joint projects. The asymmetry of priorities and resources adds to the difficulty: states with other maritime outlets can afford to wait, while those that depend on the Caspian for access have more to lose from delay. That imbalance makes quick and equitable agreement harder to reach.
THE CASPIAN FIVE AND THE ARCTIC FIVE
In his article “The Caspian Five and the Arctic Five—Critical Similarities,” Professor Bajrektarević compares the two groupings of riparian states that share a strategically valuable environment, overlapping claims, and a reluctance to see outsiders involved. He distinguishes three postures: dismissive, assertive, and reconciliatory.
As with the Arctic, all three postures can be recognized in the Caspian today. Wariness towards outside powers is visible in the ban on non-littoral armed forces and in Tehran’s argument that ratification would keep external players away. Insistence on national shares is visible in the unresolved seabed debate. Pragmatic compromise appears in bilateral arrangements such as the 2021 agreement between Azerbaijan and Turkmenistan to develop the Dostlug field.
The comparison surely has limits; The Caspian is an enclosed water body, whereas the Arctic Five border an open ocean, and the two regions are governed by different legal regimes that should not be conflated. What the comparison captures is a pattern of behavior. In both cases geography invites cooperation but does not guarantee it, and the outcome depends on whether states can reconcile their sovereign discretion with the practical demands of interdependence.
THE CASPIAN’S DOUBLE PARADOX
The Caspian’s contested legal identity has a counterpart in nature. It is called a sea, yet its landlocked setting and river inflow give it many features of a lake. Near the mouth of the Volga, salinity falls below 1%, while the central and southern basins hold roughly 13%. In the north, salinity also swings with the seasons, dropping after the spring floods and rising again in winter.
Life in the sea follows the same gradient. In the north, rivers bring in food, and most fish are freshwater species adapted to brackish water. In the south, the food chain depends more on marine plankton, and some species have ocean origins. The Caspian has fewer species than a true sea, but many of them live nowhere else.
Legal ambiguity is thus matched by ecological duality. This does not mean that ecology dictates legal status. It means that both reveal the limits of rigid categories when they are applied to an unusual system. Shared biological resources pose a problem of political geography, because dividing scarce and valuable stocks is hard when each state’s catch affects the others. A system should be governed according to its real interdependencies and internal diversity, not squeezed into a category that hides them.
LEGAL STATUS: A COMPROMISE, NOT A SETTLEMENT
For more than two decades the debate over the Caspian ran between two readings. Under the UN Convention on the Law of the Sea, each state would hold a full seabed claim. Under a lake regime, water and seabed would be shared equally among the five. The disagreement blocked a settlement for around 22 years.
The Convention on the Legal Status of the Caspian Sea, signed by the five heads of state in Aktau on 12 August 2018, chose neither reading. It created a “special legal status” and set rules for territorial waters, fishing zones, and navigation. It also prohibits the armed forces of non-littoral states from operating in the sea. The convention left the seabed question undecided. The neighboring states have to agree on borders among themselves, and Iran and the former Soviet states have long disagreed on where the dividing line should run in the south.
The Convention enters into force only when all five states have ratified it. Four have done so. In Iran, the cabinet approved the ratification bill on 22 July 2026 and sent it to parliament, and in September the foreign minister briefed the parliamentary national security committee on the text. By late October 2026, parliament has not completed ratification. Tehran presents the treaty as a way to complete the legal framework and keep foreign powers outside of the discussion and decision process. Iranian officials themselves admit that the text does not say where national shares of the sea start to be measured. That is why the issue is still sensitive inside Iran.
The retreating shoreline adds a new layer. When the water recedes, the coastline from which any median line or national zone would be drawn moves with it, so boundary questions become entangled with environmental change. That is an inference rather than an established legal position, but it indicates why a settled map of the seabed matters more as conditions shift.
Some of these difficulties were flagged early. Kaveh Madani, now at the United Nations University Institute for Water, Environment and Health, argued in 2018 that the uneven distribution of oil, gas, and environmental resources across the sea had been overlooked in the negotiations. Bilateral deals offer one way forward, as the Dostlug agreement shows. For now, however, the five states have a workable regime for shipping, fishing, and keeping outside navies out, but not a settled map of the seabed. The challenge is to build a framework coherent enough for cooperation despite differences in interpretation, priorities, and domestic politics.
RESOURCES AND ROUTES
Energy remains a major driver of Caspian geopolitics. Oil and gas exports have shaped infrastructure, partnerships, and alignments. The Baku–Tbilisi–Ceyhan pipeline and the Southern Gas Corridor carry Caspian resources to markets in the west, while the long-discussed Trans-Caspian gas pipeline continues to raise questions of commercial viability, political agreement, and environmental protection.
The Middle Corridor, officially the Trans-Caspian International Trade Route, and the INSTC show that the Caspian can serve different continental directions. They need not be seen only as rivals; depending on markets, politics, and capacity, they can complement one another.
The most pressing physical constraint is the falling water level. Scientists describe the Caspian as having reached its lowest level in the instrumental record, with the decline linked mainly to reduced river inflow, above all from the Volga, and to higher evaporation in a warming climate. In environmental governance, the five states have advanced further than on the legal-status question. The Framework Convention for the Protection of the Marine Environment of the Caspian Sea, the Tehran Convention, was signed in 2003 and entered into force on 12 August 2006 after ratification by all five governments, resting on principles such as precaution, the polluter-pays principle, and access to information.
Infrastructure alone, in other words, does not make a route. A pipeline, port, or railway can be physically complete and still be held back by inconsistent customs, fragmented regulation, a retreating shoreline, or political uncertainty. Energy diplomacy must therefore reach beyond supply contracts and export routes to coordinate infrastructure, legal arrangements, and environmental safeguards.
THE GAFG CONNECTIVITY DOCTRINE
Developed by GAFG through its Global Maritime Governance Forum (GMGF), the Connectivity Doctrine starts from a simple premise: infrastructure creates potential, but governance determines how much of it is realized. Five principles organize this approach, and each has a Caspian reading.
Systems over projects. The Caspian’s ports, ferries, railways, pipelines, and customs regimes work as one network. A new terminal at Aktau or Baku is only as useful as the rules and connections around it.
Governance as the multiplier. The quality of institutions decides how productive infrastructure becomes. The Caspian’s environmental regime, and its patchier legal one, show how differently this plays out in practice.
Interoperability as the binding constraint. Gauge mismatches, tax differences, and customs procedures hold back the Middle Corridor more than a lack of capacity does.
Complementarity over competition. The Middle Corridor and the INSTC can operate as a portfolio of routes rather than as substitutes, offering resilience to shippers and governments alike.
Connectivity as an ecosystem property. Value arises from coherence across infrastructure, regulation, and logistics, not from any single port or railway.
The Doctrine also reflects a broader shift in strategic thinking. For much of modern history, attention centered on chokepoints, and power was measured by who controlled them. GAFG’s findings suggest that the decisive question is increasingly who can connect networks around such points. Resilience comes less from dependence on one gateway than from taking part in a wider architecture of complementary routes.
The Caspian is perhaps the most literal case. It is the point where the Middle Corridor, the INSTC, and several energy routes intersect, and it is governed by five states with different regimes and priorities. The Doctrine’s contribution is to shift the question from not how to improve connections within one institutional space, but how to make connections work between systems that were never designed to fit together.
CONCLUSION
The Caspian’s importance stems from a combination of features: its unusual morphology, its disputed legal identity, its ecological diversity, its energy resources, and its position between Europe and Asia. In 2026, the same sea shows both what cooperation can achieve, in environmental protection and in bilateral energy agreements, and where it remains incomplete, in the unsettled seabed and the pending ratification in Tehran.
Whether the Caspian is a lake or a sea matters less than whether its five states can agree on governance that matches the complexity of the system they share. A shrinking shoreline, shared fish stocks, competing corridors, and overlapping claims all require the same response: institutions, rules, and data that work across borders.
A sea that no single state can control, and none can afford to ignore, may yet prove one of Eurasia’s clearest demonstrations that connection depends on rules as much as on routes.
