Taiwanese Rebreather Diver Dies During WWII Mine Recovery Operation in Japan

A Taiwanese technical diver has died while taking part in a recovery operation at a World War II-era coal mine site in Japan, an incident that has led to the suspension of further dives and renewed discussion around the risks of complex recovery missions.

According to reporting by Taiwan News, the diver was part of an international team conducting underwater surveys at the Chosei Coal Mine site in Yamaguchi Prefecture, where hundreds of forced labourers were killed in a flooding disaster in 1942. The operation was focused on locating and documenting human remains trapped inside submerged mine tunnels.

The same report states that the diver suffered convulsions while underwater and lost consciousness before being brought to the surface by fellow team members. Despite emergency response efforts and hospital treatment, the diver was later pronounced dead.

Further confirmation of the incident was provided by Japan Today, which reported that Japanese authorities were notified immediately following the accident and that all planned dives at the site were cancelled in the aftermath. Local officials indicated that the diver had been using a closed-circuit rebreather during the operation.

Additional regional coverage from Korea JoongAng Daily identified the diver as Wei Hsu, also known as Victor Hsuwei, and noted that the mission involved specialists from several countries due to the extreme hazards posed by the flooded mine environment.

While no final cause of death has been officially released, authorities cited by Taiwan News indicated that oxygen toxicity was among the suspected factors, a known risk associated with rebreather diving when oxygen partial pressure exceeds safe limits. Any definitive conclusions will depend on the results of the ongoing investigation.

The Chosei Coal Mine disaster remains a sensitive historical issue in the region, particularly due to the use of forced labour during Japan’s wartime occupation. Recovery efforts have been described by participants as both technically demanding and emotionally significant, combining advanced diving skills with historical and humanitarian objectives.

This incident serves as a stark reminder that even highly trained technical divers face serious risks when operating in confined, low-visibility, and unstable underwater environments. As investigations continue, the global diving community is likely to scrutinise both procedural safeguards and equipment considerations surrounding rebreather use in extreme recovery scenarios.