Upon arrival, emergency services found the man unconscious and not breathing.
The 29-year-old was then transported to the Townsville University Hospital in a critical condition.
The man was believed to have removed his tank to practice free diving when he became unconscious.
The man was placed in an induced coma with the decision being made to switch off his life support last night.
The tragic incident is still being investigated by both the police and Workplace Health and safety.
The coroner is currently waiting on an official report.
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