The container was reported by local fishing boats at 9:45am on Sunday (Mar 8), prompting maritime authorities to alert vessels operating in the area to exercise caution while navigating.
Officials said the white container, measuring approximately 3x6 metres and bearing the word ‘TOYOTA’, was found partially submerged in the water. The door of the container appeared dented, allowing visibility inside, but no cargo was seen floating nearby.
The container was located at coordinates 8°22′ North and 97°36′ East, about seven nautical miles southwest of Koh Hu Yong within the waters of Similan Islands National Park in Phang Nga province.
The report was received by the Phang Nga Provincial Maritime Security Centre through its network of local fishing vessels, which frequently assist authorities by reporting hazards at sea.
Following the discovery, officials coordinated with Marine Police Region 5 to issue a navigation warning advising vessels operating in the area to increase caution in order to prevent possible maritime accidents.
Fishing boats and tourist vessels operating around the Similan Islands have also been alerted to the potential hazard.
The container is believed to be debris from the SEALLOYD ARC, a cargo vessel that sank southwest of Phuket on Feb 7.
Authorities have been monitoring the aftermath of the sinking for more than a month, focusing particularly on potential environmental impacts and navigation hazards from cargo that may have been lost overboard.
Updates released by the maritime incident command centre overseeing the response say oil contamination detected near the wreck site remains limited.
Recent inspections conducted on Mar 5-6 found only small, thin oil films near the wreck site, described as scattered and discontinuous patches on the water surface.
Officials said no oil slicks were detected around several nearby islands, including Koh Racha Yai, Koh Racha Noi, Koh Kaew Noi, Koh Kaew Yai, Koh Man and Koh Aew.
A thin oil film was observed about 1.2 miles south of Koh Hei, but authorities said it was minor and remained under close monitoring.
The oil spill control team reported that most of the vessel’s pipes had already been sealed, reducing the likelihood of significant additional leakage. Analysts believe small amounts of oil may still seep from the wreck but said the situation currently appears stable.
Monitoring continues using a combination of patrol vessels, aerial surveillance and satellite data, with authorities analysing ocean conditions and oil movement modelling to track any possible spread.
If larger oil slicks are detected, response vessels may be deployed to disperse the slicks, while additional resources would be mobilised if heavier black oil is observed.
Maritime officials also confirmed that the response to the shipwreck has now entered a new phase.
After overseeing emergency operations for the past month, the incident command centre has shifted its role from direct response to law enforcement oversight.
Responsibility for salvage and recovery operations ‒ including the retrieval of containers and management of any remaining pollution ‒ has now been handed over to representatives of the ship’s owner and its insurance company.
Authorities said the transition follows an assessment that the immediate emergency phase has stabilised.
Thailand has also initiated a joint maritime accident investigation with Panama, the vessel’s flag state, under international maritime conventions.
Officials said the investigation will examine the cause of the sinking as well as the environmental and economic impacts of the incident.
Evidence is currently being compiled by multiple agencies, including the Phuket Regional Marine Office and the Thai Maritime Enforcement Command Centre Region 3 (Thai MECC 3), covering potential damage to marine resources, tourism and the costs incurred during the response operation.
Authorities said monitoring of the wreck site and surrounding waters will continue while recovery operations proceed, and vessels navigating in the area have been urged to remain alert for floating debris.