CHUUK (SCMP) — Beneath the turquoise waters of a remote Pacific atoll, a Japanese warship sunk more than 80 years ago has begun leaking fuel oil, threatening ecological disaster.
The source of the leak is the Rio de Janeiro Maru, a huge vessel used by the Imperial Japanese Navy as a submarine tender during World War II that was sunk by American bombers more than 80 years ago.
Today, as oil streams from its rusting hulk, officials in the Chuuk Islands fear this may be just the first instance of hazardous waste and toxic discharge from a “ghost fleet” of over 60 wartime wrecks that lie at the bottom of its massive lagoon.
Brad Mori, executive director of Chuuk’s Environmental Protection Agency, said the leak was first detected on September 11 when divers noticed oil escaping from the wreck of the Rio de Janeiro Maru.
Initial footage suggested as much as 4,000 litres of oil per day were escaping from the wreck, although that rate had since slowed, Mori said.
“Oil can be seen coating the mangrove roots and shorelines,” he told This Week in Asia, adding that it “threatened the livelihoods and food security” of the surrounding fishing communities.
Chuuk, home to some 50,000 people, is one of four states that comprise the Federated States of Micronesia, around 2,000km (1,240 miles) northeast of Papua New Guinea and 5,800km (3,600 miles) west of Hawaii.
Its lagoon, spanning more than 2,100 sq km (810 square miles), is famed worldwide as a diving mecca for its dozens of wrecks, many of which are former Imperial Japanese Navy ships that were sunk by the US military decades ago.
In addition to the Rio de Janeiro Maru are naval destroyers, patrol vessels, dozens of aircraft and even a submarine: the Kaidai-class I-169.
Yet the same ships that act as a major draw for dive tourists now pose an existential threat to the fishing communities living above them.
Investigators are unsure what exactly caused the Japanese wreck off of Uman Island, one of Chuuk’s largest, to start leaking oil.
The former passenger liner, later repurposed by the Japanese military, was among a fleet of ships stationed at Chuuk that the U.S Navy sank during Operation Hailstone in February 1944.
One working theory is that a large group of scuba divers may have disturbed the wreck. More than 16 were in the area on the day the spill was first reported, according to Mori.
“We think the expelled air from divers’ tanks may have displaced oil trapped in the wreck,” he said.
Other explanations include a dive boat’s anchor breaching the hull or – most ominously – the ship’s internal structure simply decaying beyond recovery, allowing oil to escape as metal corrodes and tanks rupture.
Whatever the trigger, experts agree the Rio de Janeiro Maru is unlikely to be the last rusting relic of World War II to spill oil into the pristine Pacific environment.
“We have realised that this is just the beginning of our problems,” Peter Aten, head of Chuuk State government’s historic preservation office, told This Week in Asia.
“We have over 60 shipwrecks just within the lagoon and today oil is leaking from the Rio de Janeiro [Maru], but tomorrow it will be another ship, and the next day another, and then another.”
Local authorities have scrambled to contain the spill, constructing makeshift oil catchers from water containers and deploying absorbent mats and detergents to limit the spread.
But the response has been hampered by limited resources and fragmented international assistance.
“We need the technical assistance to drain all the oil from all the wrecks to avoid further catastrophe and further damage to our environment and our livelihoods,” Aten said.
Because there was still oil in the Rio de Janeiro Maru’s storage tanks, he warned that without intervention there could be “the same situation on the same shipwreck in the future”.
A recent Australian survey estimated that as much as 39.5 million litres of oil and hazardous waste were trapped inside Chuuk’s sunken fleet, with containment tanks expected to begin failing within five years at current rates.
The majority of the wrecks are cargo ships, troop transports and naval vessels, many still holding their original fuel loads, munitions and other toxic remnants. The first leak from the “ghost fleet” was recorded in 2007 and officials say it is only a matter of time.
“This shows the urgency, the need to work on a solution immediately,” Aten said.
Japan has funded small-scale oil removal operations in the past – including by the Tokyo-based Japan Mine Action Service, which recovered more than 21,000 litres of oil from the wrecks between June 2024 and February this year – and the United States previously pledged to explore further collaboration on the clean-up.
In August last year, senior officials from both governments issued a joint statement acknowledging the environmental risks posed by the wrecks in Chuuk Lagoon. But that was before a change of government in Washington.
In the months since, the scope of the US’ contribution has not extended beyond instructing two coastguard officers who were already in the area to carry out an assessment of the problem.
Meanwhile, fishing has been halted around Uman Island, with residents warned not to consume fish or taro grown in low-lying areas. Tests are under way to determine whether freshwater sources have also been contaminated.
“The leak is greatly affecting the lives of local people, fishermen and the environment,” Aten said. “The government task forces have ordered that fishing be stopped and people cannot eat fish in the surrounding area, which is serious because fish are the main source of food for people here. Fish are also the main source of income for the people of Uman.”
Officials in Chuuk, faced with the certainty that more wrecks will eventually start leaking oil, are pleading for urgent international help to avert what they fear could become a cascading disaster.
“If assistance is not provided in time, then the results will be long-term environmental damage, mostly to our food sources and ecosystem,” Mori warned.
“There will also be widespread economic losses that impact both fishing and tourism, as well as serious risks to public health from contaminated soil, water and air, said Mori…. PACNEWS