A tugboat pilot dived for his life into Auckland's main shipping channel yesterday morning, just minutes before his vessel was swallowed up by the Waitemata Harbour.
It is not known why the 65-tonne Nautilus 3 sank. It was towing a barge at the time.
The incident is being investigatedby the Transport Accident Investigation Commission and Maritime Safety Authority deputy director Tony Martin.
Craig Harrison, Glen Hunter and Glen Bucklen, all from Oratia, were fishing when they saw the tug disappear into the sea.
Mr Harrison said he saw a man dive off the tug into the water minutes before it turned onto its side and sank.
He said the man, who was not wearing a lifejacket, swam to the barge, where another person was aboard.
Ports of Auckland spokeswoman Karren Beanland said both men were unharmed. One was able to call for help and the police arrived quickly.
She said the tugboat was owned by Thomson Towing.
Ms Beanland said no one from the company would comment on the incident and representatives could not be contacted by the Herald.
Yesterday the main concern about the sinking of the vessel was minimising environmental risks, as it contained 10,000 litres of diesel.
Diesel had leaked from the vessel, but divers quickly put measures in place to stop those leaks, which Ms Beanland described as minor.
Ports of Auckland also had booms to contain the leakage on standby before the vessel was hoisted out of the water last night by a floating crane.
The sunken vessel also caused havoc for a pleasure craft, which snapped its mast after motoring into lines connecting the crane to the Ferguson container terminal.
