Boat sinks after catching fire off Wellington's south coast

A boat caught fire off Wellington's south coast this afternoon. Photo / Supplied

A launch that caught fire off Wellington's south coast has sunk and is now submerged in 67 metres of water.

The four passengers managed to make a swift escape from what turned into a fierce fire that sent huge plumes of smoke into the air.

A Wellington Free Ambulance spokesperson confirmed all four people have been taken to hospital - two in a mild condition and two in a moderate condition.

Harbourmaster Grant Nalder said the party managed to get into a dinghy before being assisted by a local fishing boat and then by the police launch.

Emergency services were called to the scene just before midday. Photo / Supplied

By the time firefighters arrived, the Lady Elizabeth IV police launch had already gone out to the boat.

The 13m launch was leaving Wellington on a trip to the Marlborough Sounds, Nalder said.

He has no idea how the fire started.

The launch has now sunk and is submerged in water that's 67m deep, about 2km off the Taputeranga Marine Reserve, he said.

Other boats were quickly on hand to help with the rescue. Photo / Matt Fannin

"There's very little of it left and in quite deep water."

Nalder said the police launch would remain to see if any debris floated to the surface, and he warned debris could also wash ashore.

"I suspect a lot of the fuel that was on board was probably burnt. It's not ideal and it's not desirable, but unfortunately sometimes these things happen."

Four people were on board, but managed to escape the flames. Photo / Matt Fannin

Nalder said the fire had been very intense.

"It sounds like things happened very quickly," he said.

The south coast has been described as nice and calm today. Smoke from the fire was observed as far away as Lower Hutt.

Fire off South Coast of Wellington now - reported and Fire service responding pic.twitter.com/oi7LpYYsOQ

— Dr Sarb Johal (@sarb) February 15, 2022