Visual: Inside a tiny penguin's incredible 7000km trek

The endangered Fiordland penguin or tawaki has been tracked travelling 7000km in just eight weeks. Photo / Thomas Mattern

It was one of the biggest surprises scientists got in 2018: an elusive native penguin species that proved it could swim the equivalent distance between Auckland and Indonesia in just eight weeks.

The endangered Fiordland penguin or tawaki's incredible 7000km-long journey, detailed in a recent study, has been recreated in a Herald data visualisation.

The endangered species inhabits the rugged and inaccessible coastline and fiord systems of southwestern New Zealand.

But scientists had much more to learn - and a team from Otago University, Antarctic Research Trust and the Global Penguin Society have been studying its small population and breeding biology.

Throughout this so-called pre-moult journey, time was of the essence as the birds only had eight to 10 weeks before they have to make landfall again to replace their entire plumage at once.

During the moult, the penguins cannot go out to feed and have to stay on land for three weeks, so it is important for the birds to gain a lot of weight during this journey.

The study revealed, in a relatively short period of time, the penguins travelled enormous distances towards Antarctica to reach the subantarctic front almost 3000km south of New Zealand and Tasmania.

After only eight weeks they returned to the breeding sites to moult, having travelled as far as 7000km during their foraging - something scientists described as an "incredible achievement" for a flightless seabird.

They believed the penguins might be following an instinct rather than an actual need to forage in subantarctic waters.