He captured the world's attention but, now that Happy Feet has finally been released, suggestions he was bird-napped have cast a shadow over the assumption he swam to Peka Peka.
Wellington Zoo vet Lisa Argilla, who helped to free the emperor penguin from the research vessel Tangaroa yesterday, said zoo staff had discussed whether he might have been by-catch from a fishing boat in southern waters and later released closer to Wellington.
"That's very possible that that could have happened.
"There's no way we'll ever know."
After six days at sea, rough conditions subsided enough for Dr Argilla and Niwa scientists on board the Tangaroa to release Happy Feet, down a tarpaulin "hydroslide" rigged on the boat's stern ramp.
The tracker on Happy Feet shows he swam north-east for a time, before getting his bearings and heading south.
Hesitant about leaving his purpose- built, ice-filled crate, Dr Argilla had to nudge him out onto the ramp, where he stood craning his neck at crew members.
A final nudge sent him sliding in an undignified backwards descent to the ocean, to the cheers of his human entourage.
"He gave us one last look, then took off and dived and we never saw him again," Dr Argilla told The Dominion Post.
She was happy to see him back in his natural habitat.
"It's the best part of my job - I'm just hoping that he's going to live a great life."
Happy Feet was due to be released on Friday, but 130kmh winds and swells of up to 15 metres pushed the Tangaroa off course.
The boat finally reached a latitude of 51 degrees - the northern end of emperor penguins' range - overnight on Saturday. Happy Feet has been fitted with a tracking device so his progress can be monitored.
Dr Argilla said he was fit and healthy and had "just as much chance" of surviving as other juvenile emperor penguins, which tend to swim alone. He could spend up to a year in the Southern Ocean before meeting up with other juveniles and returning to Antarctica to breed.
Conservation Department spokesman Reuben Williams said DOC staff would not be investigating the possibility Happy Feet could have been dumped by a fishing crew.
- © Fairfax NZ News
How would you rate your mathematical skill?Related story: Kiwi maths performance concerns