Three minutes was all it took for a luxury launch to become engulfed in flames during a Boxing Day blaze in the Bay of Islands.
The inferno, which melted the vessel to nearly water level, marks the first boat fire in Northland in 12 months.
Emergency services fought the raging fire for four hours before the 18-metre fibreglass launch sank in the harbour waters near Moturua Island after first catching alight around 1pm.
A Coastguard New Zealand spokesperson said that, when the boat went up in flames, the owners were on a boat nearby.
An 18-year-old Auckland holidaymaker was heading to a fishing spot with his dad aboard their boat when he happened to look back towards the shore.
"I saw thick black smoke going up into the sky," the teen, who did not want to be named, said. "I knew it wasn't good as black smoke means there is something serious burning."
He said the colour of the smoke indicated fuel or other toxic materials were burning in an intense fire.
The pair, concerned people might be on board the burning launch and in danger, made a swift U-turn and steered towards the blaze, just as they overheard Coastguard's mayday call on the radio.
The teen said a message relayed over the channel described large amounts of diesel fuel aboard the vessel.
Around 10 minutes after the launch caught fire, the father and son pulled up a safe distance from the blaze.
To his relief he learned the occupants were safe: "It was really good to hear that," he said.
They, alongside many other passengers of neighbouring anchored boats, looked on in dread as nearby vessels attempted to douse the inferno until help arrived.
"I could see the flames rush throughout the cabin and all along the back. There was lots of black smoke pouring out of the top of it," he said.
Heatwaves from the blaze became obvious as the boat's fibreglass began melting.
"It was burning really hard and fast," the teen said.
Passengers and crew aboard boat tour agency, R Tucker Thompson, were anchored for a lunch stop when they looked south and spotted flames coming from above the launch's main deck.
Ben Willoughby, senior master of the R Tucker Thompson, immediately alerted Russell Radio on the VHF and were asked to help in response.
"We still had some of our own passengers on the beach and we hurriedly got them back aboard and sent our tender [ship's boat] to the stricken vessel to see if we might help in getting people off of the boat on fire," Willoughby said.
The senior master used his own boat's fire hose to attack the flames on the stricken launch.
"We were not at it for long as another large vessel came in at the same time and also started hosing the vessel which was now burnt and melted down to a few feet from the water and still pretty much an inferno," he said.
The Department of Conservation asked Willoughby to steer his vessel away from the scene.
"I was happy with this as we needed to take our own passengers back to Russell by the appointed hour but I wished that we could have stayed to help further," Willoughby said.
The attempts of sea-bound passersby were followed by Coastguard Bay of Islands. Directed by a Fire and Emergency NZ representative, volunteers arrived armed with a pump and immediately began to smother the flames with water.
They had gathered as much information from the boat's owners to ensure they knew the fuel type and whether anything explosive was onboard.
With little impact made, a Salt Air Tours helicopter armed with a monsoon bucket flew overhead and dumped around five bucket-loads of water onto the launch.
"It wasn't depressing the fire," the teen said. "It was smoking up the boat and the fire was still raging."
For around two hours, the teen and his dad had stared at the heartbreaking scene as the fire completely engulfed the launch despite the efforts of emergency services.
"I have never seen flames like that on the water. We have never seen or responded to a tragedy like this."
Fire and Emergency eventually stood down the Coastguard and helicopter after they contained the burn but not before the inferno was intensified when the diesel fuel caught alight and ravaged the doomed launch.
The distraught owners were ferried ashore by Coastguard volunteers to the comfort of family waiting in Paihia.
Booms have been placed in the water where the ship sank to control the spill of toxic materials, such as diesel, as well as buoys to allow boaties to easily navigate around the wreckage site.
Extinguishing the blaze was made difficult due to the mystery of how it started and being unable to board the launch, Coastguard NZ said.
Boaties are urged to check electrical work is carried out by a qualified electrician, that their vessel has a Warrant of Electrical Fitness, and that combustible materials are stored away from ignition points.
What to do in a fire Coastguard NZ's tips for boaties faced with flames:
•Have a fire extinguisher and fire blanket on board
•Make sure you know how to use safety equipment and fight the fire if you can
•If the fire is too dangerous, make a distress call on your VHF or cellphone and get to safety