The Government has bought St James Station in North Canterbury for $40 million to add to the conservation estate.
Prime Minister Helen Clark said the 78,196 hectare station was magnificent.
"It is located on three mountain ranges, and contains the headwaters of two major Canterbury rivers, the Waiau and the Clarence. It has 11 different tramping routes, the Amuri ski field and great mountain biking, fishing, kayaking, horse riding and hunting opportunities," she said.
"The property's almost untouched landscape is dominated by exceptional natural features such as glaciated valleys, glacial moraine deposits, streams, wetlands, lakes and high altitude tarns."
It has 430 native plant species and 30 native bird species.
The station also has historical significance and contains Maori access routes and early European sites.
The Stevenson family had owned the property since 1927. Family spokesman Mark Tavendale said the family wanted the land protected and open to the public.
Forest and Bird high country spokeswoman Sue Maturin said the purchase completed a protected corridor between the Seaward Kaikoura Range on Canterbury's east coast to the Pancake Rocks in Paparoa National Park on the West Coast.
"Forest and Bird's vision to create a coast-to-coast protected corridor is now a reality," she said.
"St James was the missing link -- it was virtually surrounded by public conservation land, but now will be a welcome part of it."
Ms Maturin said over the past 10 years seven high country parks in the South Island had been established with two pending.
"St James is especially important because it best protects the transition from dry east coast grasslands and shrublands to the wetter beech forests of the main divide.
"Except for the valley floors, most of St James is wild natural landscape, with few weeds and many threatened species, including New Zealand falcons, rock wrens and long-toed skinks."