Kiwa and Oscar, a pair of green sea turtles who have been living at Kelly Tarlton's for the past two years, have been released off the coast of Tutukaka.
The pair, aged somewhere between 10 and 20 years old, were found on 90 Mile Beach in July 2016. Staff at Kelly Tarlton's say they were "on death's door" - underweight, dehydrated, and suffering from cold shock.
They were taken to Kelly Tarlton's turtle rehabilitation centre, where they have been recovering and preparing for their release ever since. Together, they have gained around 15kg during their stay.
Staff say it is bittersweet to say goodbye to the turtles after two years bringing them back to health, but to see them "back where they're meant to be" is a happy moment for everyone.
Kiwa and Oscar received a karakia from local Ngatiwai before they set off, into an offshoot of the Australian eastern current.
The turtles have been tagged so the centre can track their progress.
There are seven types of marine turtle - five of which are found in New Zealand - and all of them are endangered or critically endangered.
Boat strikes, plastic and entanglement are all threats to turtles.
Turtles feed on jellyfish, which makes them particularly susceptible to mistaking plastic bags for food.
"The amount of plastic floating around in our oceans now mean all turtles are in dangers, said Kelly Tarlton's curator Andrew Christie.
"It's not looking good for turtle populations around the world. They might not be long in our children's generations. We need to act and do something now."
The rehabilitation centre at Kelly Tarlton's has been running since 1995. The centre takes on sick or injured turtles found in the waters around New Zealand, and has seen the release of more than 50 turtles back into the sea.