An oil spill from the grounded tanker Caroline Bezengi has spread across nearly 400 square kilometres off Oman, raising concerns about possible damage to marine ecosystems near the protected Hallaniyat Islands.
Oman’s Environment Authority said the slick covers about 390 square kilometres, or roughly 150 square miles, and extends northeast of the islands. The oil is estimated to be within around seven kilometres of the coastline.
The tanker is carrying close to one million barrels of Russian crude bound for Asia. It first reported difficulties on June 8 off Yemen, and two maritime security sources said preliminary assessments indicated that an explosion had occurred onboard.
No party has claimed responsibility for attacking the vessel.
Oman publicly details the environmental impact
The announcement marked Oman’s first public disclosure of the scale of the spill.
Authorities said they are working to contain the leak near the Hallaniyat Islands, an area protected under a nature reserve created by royal decree last year.
The reserve is home to wildlife including Arabian Sea humpback whales and Socotra cormorants.
The Environment Authority said there was no current concern for nearby facilities, including desalination plants and tourism infrastructure.
That assessment provides some reassurance for essential services, but the scale of the slick keeps attention focused on possible environmental damage.
Greenpeace estimated an even larger slick
The official estimate of 390 square kilometres is smaller than an assessment released by Greenpeace the previous week.
The environmental group estimated that the slick covered around 600 square kilometres based on satellite imagery.
The difference highlights the challenge of measuring a moving spill at sea, where wind, currents and weather conditions can change the visible surface area.
Oman’s latest assessment places the oil roughly seven kilometres from the coast.
That distance is important because the environmental consequences could become more serious if the slick reaches shallow waters or the shoreline.
Experts warn coastline impact could be severe
Tony Gutierrez, professor of environmental microbiology and biotechnology at Heriot-Watt University in Edinburgh, said a spill of this size requires a large-scale response.
He said aircraft could be needed to spray dispersants across affected waters.
Booms and other collection equipment would also be required to capture oil before it reaches the shoreline or sinks toward the seabed.
Keeping the spill offshore would significantly reduce the environmental impact compared with oil entering shallower waters and coastal ecosystems.
Coral, birds and fish are among the forms of marine life that could be affected.
Oil contamination can remain for years
Gutierrez warned that oil can persist in the environment for a long period after a major spill.
He cited the 1989 Exxon Valdez disaster in Alaska as an example of contamination remaining detectable many years later.
That risk is particularly relevant near sensitive habitats where oil can become trapped in sediments, shallow waters or coastal ecosystems.
The long-term consequences depend on factors including the type of crude, weather conditions, the effectiveness of containment efforts and how much oil ultimately reaches shore.
The source does not specify the total amount of crude that has leaked from the Caroline Bezengi.
Satellite analysis showed the spill was still expanding
An analysis by Reuters of satellite imagery and information from shipping specialists found that the slick from the stranded tanker was still spreading at the end of July.
The vessel is 274 metres long, or around 900 feet.
Its continued grounding and leakage have raised concerns that environmental damage could worsen if containment efforts fail to stop additional oil from entering the sea.
The scale of the slick means the response is likely to require coordination across monitoring, containment and recovery operations.
The tanker is carrying almost one million barrels of Russian crude
The Caroline Bezengi loaded its cargo at the Russian Black Sea port of Novorossiysk in April.
Ship-tracking data showed that it passed through the Suez Canal at the end of May on its way toward Asia.
The cargo consists of close to one million barrels of Russian oil.
That makes the incident significant not only from an environmental perspective but also because of the vessel’s role in the transport of sanctioned Russian crude.
Caroline Bezengi is part of Russia’s so-called shadow fleet
The tanker is described as part of the so-called shadow fleet used to move Russian oil.
These fleets typically consist of older vessels that often operate without Western insurance coverage and may use changing flags or ownership structures to make control and accountability more difficult to trace.
The Caroline Bezengi was built in 2001.
It was listed in public shipping databases as flying the Cameroon flag.
However, it was among 39 vessels removed from Cameroon’s ship registry in June.
Vessel faces multiple international sanctions
The tanker is subject to sanctions imposed by the European Union, Ukraine, the United Kingdom, Canada and Switzerland.
Its registered owner is Rentoor Shipmanagement Ltd, while Villar Shipmanagement Ltd is listed as its manager, according to LSEG data.
The two firms appear to be based in China.
Reuters said it was unable to immediately reach either company for comment.
The sanctions and ownership structure add another layer of complexity to any response involving insurance, liability and cleanup responsibilities.
Shadow-fleet risks extend beyond sanctions enforcement
The incident also highlights the environmental risks associated with ageing vessels used in sanctions-sensitive shipping.
Older tankers may present additional operational concerns, particularly when they lack conventional Western insurance coverage.
If a major spill occurs, questions can arise over who is financially responsible for containment and environmental restoration.
The source does not establish that the age of the Caroline Bezengi caused the incident.
However, its status as part of the shadow fleet places the spill within a broader debate about the risks associated with opaque maritime ownership and insurance arrangements.
No group has claimed responsibility for an attack
The tanker first reported problems on June 8 off Yemen.
Two maritime security sources said early assessments suggested there had been an explosion onboard.
No party has claimed responsibility for attacking the ship.
That leaves the exact cause of the incident unresolved in the information provided.
The absence of a confirmed attacker also means the environmental response remains separate from any possible investigation into the circumstances that caused the vessel to become disabled.
Desalination and tourism facilities are not currently threatened
Omani authorities said there was no current concern for nearby desalination plants or tourism facilities.
This is important because coastal desalination infrastructure can be vulnerable to oil contamination if polluted seawater reaches intake systems.
Tourism operations could also be affected if oil reaches beaches or sensitive coastal zones.
For now, authorities have indicated that those facilities are not under immediate threat.
The main focus therefore remains preventing the slick from moving closer to shore.
Wildlife around Hallaniyat Islands faces potential exposure
The Hallaniyat Islands nature reserve contains several important marine and bird species.
Arabian Sea humpback whales are among the wildlife found in the area.
Socotra cormorants also inhabit the region.
Oil contamination can affect marine mammals, birds, fish and coral through direct contact, ingestion or damage to feeding and breeding habitats.
The source does not report confirmed wildlife casualties from the spill so far.
That distinction is important: the environmental risk is significant, but the scale of actual biological damage has not yet been established.
Containment speed will be critical
The response now depends heavily on how quickly the oil can be contained before reaching more sensitive waters.
Aircraft dispersant operations, floating barriers and collection systems are among the measures identified by experts.
Weather and sea conditions will also influence the effectiveness of the response.
If currents push the slick closer to shore, cleanup becomes more difficult and environmental exposure increases.
If authorities can keep most of the oil offshore, the eventual impact could be more limited.
What to watch next
The first key issue is whether the slick continues to expand.
Authorities will also monitor its distance from the Hallaniyat Islands and the Omani coast.
Any confirmed impact on wildlife, coral or fisheries would significantly increase the environmental seriousness of the incident.
Another important factor will be whether additional oil continues to leak from the tanker.
Questions around responsibility, insurance and cleanup costs may also become more important because of the vessel’s sanctioned status and shadow-fleet links.
Conclusion
Oman says an oil spill from the grounded Caroline Bezengi tanker now covers around 390 square kilometres near the Hallaniyat Islands nature reserve.
The vessel is carrying close to one million barrels of Russian crude and is part of the so-called shadow fleet used to transport Russian oil.
Authorities say nearby desalination plants and tourism facilities are not currently under threat, but experts warn that the impact could become far more serious if the oil reaches shallow waters or the coastline.
Final Takeaway
The immediate priority is containment. The spill has already reached a substantial scale, but the final environmental cost will depend largely on whether authorities can prevent the oil from reaching the coast and sensitive marine habitats.
