Hormuz, the Red Sea, the Black Sea and the Baltic are exposing the gap between maritime law and maritime reality, write Dr Deniece Aiken and Professor Ulla Tapaninen. The crises in Hormuz, the Red Sea, the Black Sea and the Baltic are not only tests of shipping resilience. They are tests of whether international maritime law still has practical authority. Multilateralism does not unravel in an instant, but rather by virtue of rerouting orders, security warnings, emergency circulars, and a master’s decision not to enter a strait that international law says should remain open. That is what makes the present maritime moment so uncomfortable. Shipping is watching the legal architecture of global seaborne trade become conditional. For decades, the industry operated on an imperfect but powerful assumption that politics may be hostile, but sea lanes must remain usable. Yet, in addition to practice, there is also legal basis through treaties such as UNCLOS, SOLAS, MARPOL, as well as the general regulatory framework provided by the International Maritime Organization (IMO). Together, they enable ships to travel freely despite being outside national jurisdiction. The Strait of Hormuz is the newest test. Under UNCLOS, straits used for international navigation are governed by the regime of transit passage. When the IMO warned that any toll on Hormuz transit would set a dangerous precedent, it was not merely making a political point. It was defending the principle that an international strait is not a coastal state’s turnstile. The disruption in Hormuz is not just an energy-market event, but more so a challenge to the legal foundation on which global trade depends. Reuters reported in March 2026 that conflict around Hormuz had affected around 20,000 seafarers on nearly 2,000 ships west of the strait, with shipping in the Gulf and around Hormuz near a standstill after threats against vessels using the waterway. The inability of commercial vessels to pass through a strait required by international law to remain open is a different kind of problem entirely. It is the gap between legal entitlement and operational reality. That same month, Strait of Hormuz transits had fallen by more than 80% after vessels were struck and war-risk insurance was cancelled. The situation demonstrated that the strait was practically closed, though not by Iran, but rather by shipping itself. The Red Sea exposed the same gap. As much as freedom of navigation is legally possible, ships still sail through practical realities that are based on the presence of missiles, drones, mines, misidentification, and war risk premiums, which decide whether the route is accessible or not. The ISPS Code was built to manage threats. It was not designed to replace geopolitical order. The Black Sea illustrates the problem even more sharply. The IMO has described the conflict between Russia and Ukraine as a serious and immediate threat to the safety and security of crews and vessels operating in the region. It also highlighted Ukraine’s special maritime corridor for commercial vessels heading to and from Ukrainian ports. This is important because the entire IMO regime works through the involvement of states. For the Baltic region, maritime security is no longer just about ships, cargo, and seaways. It is also about cables, pipelines, offshore assets, sanctions enforcement, shadow fleets and a state’s obligation to secure its vital maritime infrastructure. Under the provisions of the UNCLOS, free