New Zealand's defence force has launched a formal court of inquiry into the "shocking" sinking of the HMNZS Manawanui, which sank after striking a reef in Samoa's south.
On Saturday night, the 85-metre vessel ran aground around 2 kilometres south of the Samoan village of Siumu, causing Captain Yvonne Gray to order crew to abandon ship via life rafts and smaller vessels.
All 75 onboard — including seven scientists and four non-NZ military personnel — made it to shore in rough seas, which took at least 5 hours during the night.
HMNZS Manawanui ran aground off the south coast of Upolu while conducting a reef survey. (RNZ: Profile Boats )
One life raft capsized on the reef, requiring those on board to walk to shore on the reef, where several required medical treatment.
On Sunday morning, the listing boat caught fire and sank.
The embarrassing incident is NZ's first naval loss during peacetime, and its first since World War II.
It has also launched an urgent clean-up job, and investigation into whether the wreckage can be salvaged from the sea floor.
Defence Minister Judith Collins said her top priority, given all crew were safely transported from the sinking vessel early on Sunday, was "the environmental side".
"It's got a lot of oil on board. It's got all sorts of things. It's got lubricating oil, hydraulic oil, diesel … it's got a lot of stuff in it," she told Newstalk ZB.
"I don't think we can leave it like that."
All 75 on board the HMNZS Manawanui made it to shore safely. (Supplied: Samoa Fire and Emergency Services Authority)
Samoan man Manu Percival, interviewed by Radio NZ on Monday, said oil was identifiable along the coast for several kilometres which would have a "massive impact".
"The impact is crazy. There's so many green sea turtles in that area. So many sting rays," he said.
"Right where the ship went down just inland, there's a huge lagoon of brackish water and it houses all sort of animals. Coconut crabs, everything. They'll all be affected. Everything.
"That part of the ocean is full of the grass that turtles eat. That's going to have oil all over it for sure."
Mr Percival said the sea was "big time" treacherous and locals avoided it.
The Manawanui, a specialist hydrographic vessel, was in the region to map the ocean floor in the area for the first time in almost 40 years.
"They were dealing with a reef that has changed … there have been earthquakes, there's been tsunamis, there's been changes to that reef and that's why that survey was taking place," Ms Collins said.
She said the court of inquiry, which will take up to two months, would explain how the ship lost power and ended up on the reef.
Whether the wreckage will be salvaged will depend on how deep it is below the surface, which was being investigated.
Divers aboard the HMNZS Manawanui back in 2014. (AAP: NZN Image/Julia Hollingsworth)
Acting Samoan Prime Minister Afioga Tuala Tevaga Iosefo Ponifasio told a press conference he believed it was "not recoverable".
The lost ship is the latest setback for New Zealand's defence force, which has been hit by attrition — like many countries — and belt-tightening in recent years.
Former defence minister Andrew Little described the pandemic-era staff loss as "a big hollowing out", with the 2023 headcount equivalent to 2015 levels.
In 2023, four of the navy's nine vessels were unable to be staffed, which Ms Collins told AAP was a "real concern".
It is not clear whether understaffing or other budget cuts had an impact on the ship running aground, which will be the subject of the defence probe.
AAP