Ship-to-ship transfers in the Gulf of Oman moved 8 million barrels daily in September as owners avoid the Strait of Hormuz. Iran blacklisted over 70 vessels, and the Mombasa B continued shuttle runs after a July missile attack killed one crew member.
A flexible network of ship-to-ship transfers has emerged as a critical workaround for keeping oil moving while the Strait of Hormuz remains a high-risk transit, and Hormuz Shuttle Tankers now sit at the center of this wartime adaptation. On September 16, the Hong Kong-flagged Cospearl Lake was completing its voyage to Dalian, China, carrying two million barrels collected from another tanker in the Fujairah lightering zone rather than loaded directly in the Persian Gulf.
The UAE has led this process, with ADNOC chartering vessels like the Mombasa B, which continued shuttle runs even after an Iranian cruise missile attack in July killed one crew member and injured eight others. Loadings from the Persian Gulf and Gulf of Oman reached roughly 8 million barrels per day in September, up from 5.8 million in August, as Iraqi crude increasingly moves via STS transfers.
Yet Hormuz Shuttle Tankers remain vulnerable: Iran’s Persian Gulf Strait Authority has blacklisted over 70 vessels and signaled that monitoring will continue. This workaround requires more tankers, lacks terminal efficiency, and cannot restore prewar volumes of 20 million barrels per day. Understanding how this shuttle trade operates is essential for assessing both its resilience and its limits.
Hormuz Shuttle Tankers Keep Oil Moving
On September 16, Hong Kong-flagged crude oil tanker Cospearl Lake (IMO 9337171) was finishing the last leg of its voyage to Dalian, China, carrying a crude oil cargo loaded last month in the Fujairah lightering zone in the Gulf of Oman. The 2 million barrels onboard the Chinese state-owned very large crude carrier (VLCC) were collected from another tanker instead of being loaded directly in the Persian Gulf, according to shipping data.
The Cospearl Lake is one of many cases showing how certain owners and charterers are preferring to pick up oil cargoes via ship-to-ship (STS) transfers in the Gulf of Oman instead of sailing through the Strait of Hormuz, which remains a high-risk and costly transit. Meanwhile, the vessels that have been shuttling oil from within the Gulf include tankers owned or operated by regional oil and gas exporters, as well as tankers belonging to selected shipowners in the market willing to take the risks associated with making a transit of the Strait.
These shuttle operations have been critical for regional exporters, particularly the United Arab Emirates (UAE) which has been at the forefront of this process, as well as global oil markets. These operations complement non-shuttle transits; i.e. tankers that continue directly to their final destinations instead of transferring cargoes to other vessels.
However, the shuttle trade, which is a flexible network to keep oil moving amid the disruption in the Strait of Hormuz, will likely remain a target for further Iranian attacks. Iran’s Persian Gulf Strait Authority (PGSA) has been signaling that its monitoring tankers involved in STS transfers, warning others against “cooperating” with these ships. The PGSA has so far added over 70 vessels (tankers and non-tankers) to its so-called blacklist of “non-compliant” vessels not following “Iranian arrangements” in this waterway.
A tale of two tankers indicate the trends
The Cospearl Lake, which is linked to Cosco Shipping Corp, was among the first China-associated tankers that managed to exit the Strait of Hormuz in April amid a brief ceasefire, after weeks of being stranded in the Gulf region due to the Iran war.
On April 11, the tanker, which was carrying an Iraqi cargo of Basrah Medium crude loaded in early March, sailed out of the region using an Iran-controlled route. Since that time, it has not been observed crossing the waterway again, available shipping data from Kpler and MarineTraffic show. Instead, data indicates that the tanker has loaded Middle Eastern crude at least twice between June and August in the Gulf of Oman. Towards the end of August, it engaged in a ship-to-ship transfer of crude oil cargo. Verifying each tanker in the STS process is not always straightforward, and sometimes the vessels that shuttled and transferred the cargoes via STS remain unconfirmed.
Mombasa B Shuttles Despite Iranian Attack
Among the several tankers that have been shuttling oil from the Gulf region to the Gulf of Oman is the Mombasa B (IMO 9739501), a vessel selected by the author of this article to show how the shuttle trade operates. Examining the entry of the Mombasa B into the shuttle operations reveals not only how oil is ferried for transfers in the Gulf of Oman.
It also shows how some regional state-owned companies, like the UAE’s ADNOC Logistics & Services (more on this below), utilize tankers under their control to maintain the shuttle trade, and even expand it. In addition, the case of the Mombasa B shows that despite an Iranian attack against it in July, the tanker was not deterred from crossing the Strait of Hormuz again.
The Mombasa B, a VLCC, was chartered by the UAE’s ADNOC from VLCC owner Sinokor Maritime, which reportedly began leasing tankers to the UAE for the shuttle runs “from at least mid-April,” according to a report by Bloomberg.
The vessel was tracked entering the Persian Gulf region in ballast on April 11 via an Iran-controlled route around Larak Island, data from Kpler and MarineTraffic show. Since that time, the tanker has been moving between the Gulf region, where it has been loading at terminals, and the Gulf of Oman, where it has been transferring the cargoes to waiting tankers. Since June, the Mombasa B has been engaged in shuttle runs, most of which have been conducted as dark transits, i.e., without transmitting AIS data, especially while sailing through the Strait.
On July 13, Iranian forces targeted the Mombasa B while it was transiting the waterway. The UAE Ministry of Defense said that the tanker was targeted by cruise missiles. An Indian crew member aboard the tanker was killed in the attack, and eight other seafarers were injured. However, the attack did not put the tanker out of service, although the vessel sustained material damage as a result of a fire onboard, which was brought under control.
The Mombasa B is now on Iran’s list of 77 “non-compliant” vessels.
Expansion and flexibility despite constraints and risks
The UAE has been leading the VLCC shuttle trade as it expands its shipping capacity. On August 7, ADNOC Logistics & Services (L&S) announced the acquisition of six VLCCs on the secondary market, scheduled for delivery in Q3 2026. Other regional countries that have also been using their tankers for shuttle runs include Kuwait.
The VLCCs owned by ADNOC don’t carry only Emirati crude. Data confirms reports that some ADNOC tankers have been lifting Iraqi Basrah crude and transiting the Strait of Hormuz via the U.S.-facilitated Omani corridor, a sign of a regional network working to keep oil flowing despite ongoing Iranian risks that are likely to evolve as this network expands too.
For instance, in August, Liberia-flagged Al Maqam (IMO 9732577), a VLCC owned by ADNOC since August 2026 – as shown in one shipping database – loaded about 2 million barrels of Basrah Medium in Iraq, according to figures published by Iraq’s State Oil Marketing Organization (SOMO).
Omani Corridor Handles Iraqi Crude
Crude and condensate loadings from the Persian Gulf stood at about 5.8 million barrels per day (mbpd) in August, including loadings in the Gulf of Oman via STS transfers, Kpler’s data show. These figures have increased materially so far in September, hovering around 8 mbpd. A notable rise was observed in Iraqi loadings deep inside the Gulf, standing at around 2.6 mbpd so far this month, compared with 1.6 mbpd in August and around 984,000 bpd in July. Additional Iraqi barrels could also be attempting to leave in the dark (no AIS data) or via shuttle tankers, and have yet to be captured in these figures.
Buyers of Iraqi crude now reportedly have the option to pick up cargoes via STS transfers in the Gulf of Oman instead of having to load them within the Gulf, Bloomberg reported on August 27.
The shuttle trade can be viewed as being as important as existing regional oil pipelines, which countries like the UAE and Saudi Arabia have been relying on to reroute some volumes away from the Strait of Hormuz due to Iranian threats. In the case of Saudi Arabia specifically, the kingdom may look at offering more cargoes via ship-to-ship transfers in the Gulf of Oman due to the recent attack on its East-West pipeline, which led to its shutdown impacting exports out of Saudi Red Sea terminals.
Hormuz Shuttle Tankers Face Iran Threat
Despite the success in keeping oil flowing, the current shuttle runs do not mean a return to pre-war loading average in the Gulf region of around 20 mbpd of non-Iranian crude, condensate and oil products. This way of trading, despite its flexibility, remains a workaround amid a war. It requires more tankers to keep increasing oil volumes and lacks the efficiency of conventional loadings of cargoes at terminals which are then transported directly to importers. It is also not immune to Iranian attacks, as data shows that some tankers involved in the shuttle runs have been targeted.
If Iran’s own crude oil loadings, which according to Vortexa plummeted to below 500,000 bpd in August from around 2 mbpd earlier in 2026, remain constrained for a longer period due to the US naval blockade, there is a possibility that Iran may seek to further disrupt the shuttle runs. In addition, Tehran should be expected in this case to keep risks high along the Omani corridor as well as within the Persian Gulf – where Iranian forces may have more visibility into certain areas, such as Iraqi waters. On September 9, a storage tanker for fuel oil was struck in Iraqi waters by an unknown projectile.