The number of ships passing through the Strait of Hormuz is increasing as after a $2mn fee was established and the inform permits-for-passage system is smoothed by use.

Commercial shipping through the Strait of Hormuz is increasingly being diverted into Iranian territorial waters via a route dubbed the “Tehran Toll Booth” that avoids the traditional two sea-lanes in international waters in the middle of the strait and passes into Iran’s territorial waters much closer to the northern shore, well within range of Iran’s drones and missiles.

More than 20 vessels have now taken the detour between Iran’s Qeshm and Larak islands in the Strait, according to Lloyd’s List, with traffic picking up over the weekend despite continued disruption across the chokepoint.

Analysis by Lloyd’s List Intelligence showed that at least 16 vessels transited the strait since March 20, with 12 sailing through the controlled corridor. Thirteen vessels were heading eastbound out of the Gulf, while three travelled westbound.

Among those using the route were two so-called “zombie” tankers, which transited “impersonating dead oil and gas carriers”, highlighting efforts by some operators to obscure vessel identities in a high-risk environment.

At least two ships are understood to have paid Iran for passage, with one reported fee of about $2mn, underscoring the emergence of what industry observers describe as a de facto toll system. The corridor is monitored by Iran’s Islamic Revolutionary Guard Corps, which is said to be verifying vessel details and, in some cases, charging for transit.

The shift in routing follows a sharp rise in maritime insecurity since late February. More than 20 military strikes involving commercial vessels and offshore infrastructure have been recorded since February 28, leading insurance companies to hike fees dramatically or suspend policies completely.

While overall volumes remain well below the 100-plus ships that normally transit the Strait daily, the recent uptick in crossings suggests some operators are adapting to the new informal arrangements. The amount of oil now leaving the Gulf has risen to around 8mn b/d, according to bne IntelliNews estimates, if the Saudi westward pipelines that terminate at the port of Yanbu on the Red Sea are included, down from the 20mn b/d pre-war.