Conservationist Pete Bethune has been stabbed in the chest after being attacked by two men in Santander, Brazil.
Mr Bethune, the captain of Earthrace Conservation and former Sea Shepherd captain, is in a stable condition and has been discharged from hospital.
Larisa Kellett, director of operations for the initiative, said he had been trying to hire a boat in the local seaside town in the morning, local time, when he was approached by two men.
She said the men initially tried to slit his throat with a "long rusty knife".
They then lunged at him again and stabbed him in the chest, she said. He also suffered lacerations to other parts of his body.
"Life is so cheap in those places. He said earlier that it felt like someone was watching him but it could have been a random robbery," Ms Kellett said.
"Nurses told him that they thought his ribs stopped his lung from being punctured.
Ms Kellett said he was robbed of his cellphone, but he managed a getaway on a motorbike to his hotel in Macapa where he patched himself up.
He then took himself to Macapa Hospital where his wound was cleaned to prevent and infection, and was stitched up before being discharged.
Ms Kellet said he was "laying low in a motel room" until the Earthrace team could get him on flights back to New Zealand.
Local police are investigating the incident.
Mr Bethune has been working with the Earthrace team in the Amazon for several months on conservation issues, such as illegal logging and the illegal pet trade.