A vast oil slick from a damaged tanker has begun reaching Oman’s coastline, threatening a protected marine area and raising fears of one of the world’s most serious oil-spill disasters in years.

Oman’s environmental authorities confirmed that oil had reached the mainland. The spill could affect about 40 kilometres of coastline near Ras Madraka as well as Masirah Island, according to official estimates cited by Reuters.

Satellite analysis indicates that the slick covers more than 2,000 square kilometres. Its scale has increased rapidly since late July, while response efforts have been complicated by conflict, sanctions and uncertainty over who will pay for the cleanup.

The tanker, Caroline Bezengi, was carrying an estimated 800,000 barrels of Russian oil and was under international sanctions. It ran aground on June 30 after reporting difficulties off Yemen earlier in June. Maritime sources said the ship may have suffered a blast, but no group has claimed responsibility and the precise cause has not been established publicly.

The vessel’s route placed it near two separate conflict zones. It sailed from Russia’s Black Sea coast, where Ukraine has targeted Russian oil infrastructure and ships, and later passed Yemen, where Houthi forces have attacked commercial vessels during the wider US–Israeli war with Iran.

The ecological threat is substantial. The tanker is leaking near an Omani marine nature reserve that supports Arabian Sea humpback whales, Socotra cormorants and other wildlife. Oil can damage coastal habitats, contaminate feeding areas and affect fisheries long after the visible slick is removed.

Oil-spill response usually involves floating booms, skimmers, shoreline barriers and the controlled removal of contaminated material. Those measures become far less effective once oil has spread across a vast area or weather breaks it into smaller patches. Heat, waves and currents can also drive pollutants into beaches and shallow ecosystems.

Cleanup responsibility is also unusually complex. The International Oil Pollution Compensation Funds said it would not cover costs because the incident is being treated as an act of war rather than a conventional shipping accident. Sanctions may further restrict payments, insurance assistance and access to contractors.

The United Nations’ International Maritime Organization said contingency planning was in place. However, oil-spill response becomes more difficult as slicks spread over a wide area and reach beaches, mangroves or wildlife habitats.

The incident has a direct India connection. Reuters reported that the tanker was sailing from Russia towards India. India has become a major buyer of Russian crude, and the broader reliance on ageing or opaque “shadow fleet” vessels has increased concern about safety, insurance and environmental liability.

The spill does not by itself threaten India’s oil supply, but it highlights the hidden risks in conflict-era energy trade. Sanctioned vessels may have complicated ownership structures, uncertain insurance coverage and limited access to emergency assistance.

Coastal communities may face losses even before long-term ecological damage is measured. Fishing restrictions, contaminated catches, beach closures and cleanup activity can affect livelihoods and tourism. Determining compensation will be particularly difficult if international funds decline involvement and the ship’s insurers or owners are constrained by sanctions.

The immediate priorities are to contain the leaking oil, protect Oman’s coastline and wildlife, and establish responsibility for long-term restoration. Without rapid action, an accident already spread across thousands of square kilometres could leave ecological and economic damage lasting for years.