A sharp rise in "dark" oil tankers traversing the Strait of Hormuz with AIS transponders disabled is heightening the danger of catastrophic collisions and spills, according to maritime analysts. Vessel crews are deliberately switching off location beacons to evade attacks by Iran, which has seized or harassed commercial ships in the strategic waterway since 2019.

The practice creates a "dark fleet" that operates blind to other traffic, coast guards, and satellite monitoring. Without automatic identification signals, ships cannot see each other on radar-style displays, dramatically increasing close-quarters encounters in the narrow strait where 20 million barrels of oil pass daily.

Insurance premiums for Hormuz transits have surged, and some owners now reroute around the Cape of Good Hope despite the 10-day delay and added fuel cost. The International Maritime Organization has urged flag states to enforce AIS compliance, but enforcement remains patchy.

Analysts warn that a single major spill in the confined channel could halt exports from Saudi Arabia, Iraq, the UAE, and Kuwait simultaneously, triggering a global supply shock and environmental disaster.