It took a council vessel, a team of divers and flotation bags to finally recover the wreckage of the stricken fishing boat Enchanter from the bottom of the sea.
The Mangōnui-based charter boat capsized off Murimotu, near North Cape, in wild weather on March 20.
Five of the 10 men on board died with the other five winched to safety by the Northland Rescue Helicopter.
The tragedy is being investigated by the Transport Accident Investigation Commission — which reports on serious aviation, marine and rail accidents — as well as police, Maritime NZ and possibly WorkSafe.
Examining the wreckage is a key part of any investigation but in this case, the hull rolled and sank as it was being towed to Houhora Harbour by salvage contractors on March 23.
Initially, it was thought to be too deep and too costly for a second salvage attempt, Northland harbourmaster Jim Lyle said.
''But we had another look and the divers reckoned it could be done. The insurers agreed so we went back and lifted it from 26 metres,'' he said.
The ''tricky" salvage took place on March 31 and made use of a Northland Regional Council vessel, professional divers and dive bags to float the wreckage to the surface.
It was then towed to Houhora Heads and beached near the motor camp, where a tow truck pulled it ashore.
Investigators from TAIC, which was in charge of the operation, examined the wreckage on-site on April 1.
Lyle said the vessel was too large to be lifted out of the water at Pukenui wharf. A crane barge, which had been brought in for the initial salvage attempt, had long since departed.
The salvage was deliberately kept low-key, with details only starting to emerge this week.
TAIC spokesman Simon Pleasant said the wreckage had since been removed and because it was evidence in an ongoing inquiry, stored at a secure location.
TAIC investigators had now spoken to everyone they needed to for the initial part of the evidence-gathering phase.
It was possible more interviews would be required as the investigation progressed.
''We are still in the very early stages of investigating this tragedy. It's an awful thing for all the families concerned.''
The evidence-gathering phase was expected to continue for several months.
It would include collecting meteorological data, any navigation data that could be obtained, and information about other vessels at sea at the time.
''We'll be drawing on all of that, talking to the people involved and examining the physical evidence,'' Pleasant said.
The investigation would pass through a number of stages before a final report spelled out what needed to be done to prevent a similar tragedy from happening again.
''We don't do blame. We are forward-looking and keen to establish the broader circumstances of what leads to an accident rather than just the immediate causes.''