The creation of Rakiura National Park will protect Stewart Island's untouched natural and scenic beauty for future generations, Prime Minister Helen Clark said yesterday.
Miss Clark, Conservation Minister Sandra Lee and mountaineer Sir Edmund Hillary attended the opening ceremony at Lee Bay on the island.
It is New Zealand's 14th national park.
"Stewart Island is one of the largest islands in the world where natural features are relatively unchanged by human contact," Miss Clark said.
The park covers 157,000ha and 85 per cent of the island, excluding a buffer zone around Halfmoon Bay township, private and Maori-owned lands and public roads.
With its unspoiled soggy native forest, windswept granite mountains and wild beach coastline, Rakiura National Park is more untouched than any other park or part of New Zealand, according to conservation experts.
It is also the world's southernmost national park.
It is the only national park where weka, kaka and kiwi are relatively safe because there are no stoats, ferrets and weasels.
The opening today was marked with the unveiling of a giant chain link sculpture.
The chain symbolised Stewart Island's legendary link to the South Island as the anchor to Maui's canoe.
Ms Lee said the park would protect the island's unique native plants and wildlife.
"Possums, deer, feral cats and rats have all taken their toll on the island's ecosystems but active conservation management will enhance its conservation values," she said.
A study under way would make recommendations on the government's contribution to the infrastructure costs associated with the new park.
The park's opening coincided with the announcement of the Rakiura Education Trust, developed to help Stewart Islanders reach their full academic potential.
The government has given $10,000 to help establish the trust.
The creation of the park has not been without controversy, with islanders concerned their rates would be used to pay for facilities to be upgraded to meet tourist demands.
As well, a flyer sent to residents this week urged them to protest at the opening over plans to use 1080 poison to eradicate pests on the island.
The flyer, distributed by conservation activist Rodney Hansen, questioned whether the opening was a day of celebration or protest.