Hormuz and the Black Sea: A Lesson from History

Whenever tensions rise in the Strait of Hormuz, attention naturally turns to energy markets, naval deployments and freedom of navigation. Yet there is also a historical lesson worth considering. Strategic waterways do not merely control access to a strait. Under certain circumstances, they can determine the fate of an entire sea. 

The Black Sea provides a striking example. 

Today, international attention focuses on Hormuz because it serves as the gateway to the Persian Gulf. A significant portion of global energy exports passes through this narrow corridor. The concern is straightforward: if access through the strait is disrupted, the consequences extend far beyond the immediate region. 

History shows that similar concerns are not new. 

For centuries, control of the Bosporus and the Dardanelles gave the Ottoman Empire extraordinary influence over access to the Black Sea. Following the conquest of Constantinople, the Ottoman authorities gradually established a system under which foreign powers had only limited access to Black Sea trade and navigation. Although the Black Sea never formally ceased to be an international body of water, it increasingly functioned as an exclusive strategic sphere controlled through the straits. 

In practical terms, the Black Sea came remarkably close to becoming a closed maritime space. 

As the author of Völkerrechtliche Rechtslage des Kaspischen Meeres (The International Legal Status of the Caspian Sea), I have spent years examining how geography, politics and international law interact in strategically important maritime regions. One recurring lesson is that control over a narrow gateway often matters more than control over the sea itself. The power to regulate entry and exit can ultimately shape the entire legal and political character of a maritime basin. 

The modern legal order developed partly in response to this reality. International law generally favours open navigation and seeks to prevent strategic chokepoints from becoming instruments of exclusive control. Yet recent debates surrounding Hormuz demonstrate that the underlying tensions have not disappeared. 

The current regime of the Black Sea is shaped above all by the 1936 Montreux Convention Regarding the Regime of the Straits. Its solution is deliberately balanced. On the one hand, Türkiye enjoys a special and exclusive position as the territorial State controlling the Bosporus, the Sea of Marmara and the Dardanelles. It receives prior notifications for the passage of warships, applies detailed limitations on naval transit, and may exercise far-reaching discretion in wartime or when it considers itself threatened by imminent danger of war. These rules give Türkiye a gatekeeper role that no other coastal State of the Black Sea possesses. 

On the other hand, the same regime preserves the essential openness of the route. Merchant vessels continue to enjoy freedom of passage through the Turkish Straits in peacetime, subject to navigation safety and traffic-management rules. The restrictions are directed mainly at vessels of war, especially those belonging to non-Black Sea States, which face limits on tonnage, duration of stay and advance notification. In this way, Montreux does not simply close the Black Sea behind a Turkish gate. Rather, it separates commercial navigation from naval power projection: trade remains open, while military access is regulated in the interest of regional stability. 

The comparison between Hormuz and the Black Sea is therefore more than historical curiosity. Both regions highlight the strategic significance of maritime gateways. Both remind us that access can be as important as territory. And both demonstrate how the control of a single strait may influence the security and prosperity of an entire region. 

The Black Sea’s history offers a useful warning. Seas are not isolated geographical entities. Their openness often depends on the narrow passages connecting them to the wider world. 

That is why developments in the Strait of Hormuz matter not only for the Persian Gulf, but for the broader international order that relies on freedom of navigation and access to global trade routes.