A Te Anau man was out for a Sunday drive when a live snake slithered out of the dashboard and dropped between his feet.
Jimmy Calder had recently imported his Nissan Navara in from Australia, where he had kept the vehicle to drive while on holiday.
His son Warren Calder says his father was driving along when the snake popped out of the dashboard - "It actually popped down between his legs too."
He says it was thought the reptile was a tree snake. Tree snakes are not venomous and are common to many parts of Australia.
Warren Calder says his dad was not worried when the snake popped out as "he's been around that stuff a lot before".
He says the snake had probably been hiding away because of Te Anau's recent cold weather, but would have come out with the warmer weather.
A police spokeswoman says the man drove to the Te Anau police station about 2pm, saying he had found the live snake in his vehicle.
"Police have ensured the animal is secured in the vehicle and Ministry for Primary Industries staff will be dealing with it."
A Ministry for Primary Industries (MPI) spokeswoman says the snake was "not a risk and it's not known to be dangerous". She said a snake expert had identified it from a photo as a Australian tree snake, but photo identifications were never 100 per cent reliable.
She says a quarantine inspector had arrived in Te Anau. They would be moving the vehicle to quarantine in a secure place, where it would be fumigated, which would euthanise the snake.
The spokeswoman says it was unknown how the snake got into the country undetected, and MPI would be checking how the vehicle came into the country and what fumigation processes it had gone through. The situation was being treated seriously.
New Zealand has a complete ban on snakes, which extends to zoos, meaning it's very rare for Kiwis to see them.
Stowaway snakes are uncommon in New Zealand, but not unheard of. A brown tree snake was found to have hitched a ride on a private jet to Auckland airport in March 2016.
The country does have one species of snake which is technically a native – the venomous yellow-bellied sea snake. One was found washed up on a Taranaki beach in May 2016. The sea snakes are usually found closer to the tropics, but have washed up on NZ beaches for decades.