Nearly two-thirds of tanker crossings through the Strait of Hormuz since July 14 took place without active tracking signals, leaving oil traders, shipowners and regulators with an increasingly incomplete picture of one of the world’s most important energy routes.

The loss of visibility also carries direct consequences for Cyprus’ shipping sector, complicating route planning, chartering decisions, sanctions checks and insurance assessments at a time when every voyage through the waterway carries greater financial and operational risk. 

According to the latest Signal Group data, 62 per cent of 102 recorded tanker transits were completed with the Automatic Identification System, or AIS, switched off. 

The practice was particularly widespread among crude carriers, with 33 of 42 transits, 79 per cent, taking place without an active signal. 

By comparison, 30 of the 60 clean petroleum and product tanker crossings were AIS-dark, meaning the rate among those vessels stood at 50 per cent. 

The ownership profile of the ships adds another layer of uncertainty. Signal Group classified 56 per cent of all transits as linked to non-transparent interests, including 29 involving sanctioned-fleet vessels, 17 connected to opaque ownership structures and 11 attributed to the so-called ghost fleet. 

The remaining 44 per cent were controlled by named and transparent owners. 

Traffic continued in both directions, with 55 ships travelling from east to west and 47 moving in the opposite direction. However, identifying the precise lane used proved far more difficult. 

Only four transits were confirmed through the Omani lane, compared with 45 along the Iranian side of the strait. For the remaining 53 voyages, AIS coverage was insufficient to establish the route reliably. 

This means that more than half of the tanker movements included in the analysis cannot be fully reconstructed through conventional ship-tracking platforms, weakening estimates of exports, cargo destinations and the volume of crude and petroleum products leaving the Persian Gulf. 

The disappearing signals do not necessarily point to illegal activity. Under IMO guidance, a ship’s master may switch off AIS when continuing to transmit could compromise the vessel’s safety or security, including where there is an imminent threat of attack. 

At the same time, AIS manipulation has previously been used to conceal sanctions breaches and ship-to-ship transfers. BIMCO guidance therefore stresses that the absence of a signal alone is not enough to prove wrongdoing and that the circumstances surrounding each blackout must be examined. 

Separate figures from Lloyd’s List Intelligence confirm that dark voyages have become increasingly common. Nearly 70 per cent of observed tanker transits during the week of July 13 to 19 were carried out without AIS, up from 55 per cent a week earlier and 42 per cent two weeks before that. 

Meanwhile, the number of ships using the waterway remains far below normal levels. Kpler data showed that just six vessels crossed on Monday, compared with a ten-day average of about 11 and the pre-war norm of 130 to 140 ships per day. 

The information gap matters far beyond the shipping industry. The US Energy Information Administration estimates that 20.9 million barrels of oil per day passed through Hormuz during the first half of 2025, equal to about 20 per cent of global petroleum consumption and one-quarter of internationally traded seaborne oil. 

The strait also handled more than 20 per cent of global liquefied natural gas trade, mainly through exports from Qatar. 

Commercial risks have risen accordingly. War-risk premiums have ranged between 3 and 10 per cent of a ship’s value at different points during the conflict, compared with about 0.25 per cent before hostilities. For a tanker worth $100 million, that translates into a potential insurance bill of between $3 million and $10 million for a voyage through the region. 

Hormuz now has two traffic pictures. The vessels visible on tracking screens and those whose movements must be reconstructed afterwards. For shipping companies and energy markets trying to determine how much oil is moving, where it is heading and who controls it, the second picture is becoming the one that matters most.