Beach-goers yesterday spoke of the horror of seeing the plane crash into the harbour.
There were about 200 people on the beach at the time, and many rushed to help rescue those on board, while boaties and kayakers also made their way to the scene as the plane began to sink under the water.
Lane Hannah was driving in Raglan's township when he saw the plane coming back towards the air strip.
"I said to my wife, 'Oh geez, that plane doesn't look like it's going to hit the runway'. It looked like it was coming in on an odd angle and it was pretty low at the time."
A couple of minutes later, the sirens of emergency services were sounding and people were running towards the harbour.
When Mr Hannah, who is on holiday from Auckland, got to the beach there was "just a bit of a tail sticking out of the water".
"They are quite lucky, really, in a sense, that this hit the water as opposed to getting any closer [to the runway]. Because it is effectively parallel with a grass area where there are hundreds of people."
Mr Hannah said he saw the woman from the plane being taken to an ambulance, which then drove to an open area where she was transferred into the waiting Westpac helicopter.
Maria Puaula, who was about to start her shift at the Raglan Kopua Holiday Park, said: "People were just looking up and thinking what the ...?' and then it happened."
Ms Puaula was walking over the bridge on Raglan Harbour with some friends when she heard the plane, "but it just seemed to be puttering".
"We thought, 'That doesn't sound good', so we looked up and it was quite low."
Ms Puaula said the plane swerved to miss the township and headed left towards the harbour.
She thought the plane was going to recover but it hovered and then crashed about 100m offshore.
Boaties and "heaps of kayaking people" arrived at the stricken aircraft very quickly.
"It up-turned and started to sink slowly. As it started to sink, we saw a couple of heads pop out.
"Everything went crazy and we just waited on the shore. There seemed to be three people on the plane."
Raglan Coastguard president Wally Hawken said the plane was in relatively shallow water, which would make its retrieval easier.
A spokesman for the Hamilton-based Westpac Rescue Helicopter, which flew the seriously injured woman to hospital, praised the local rescue services, in particular the Raglan Coast Guard, for their "incredible initial response".