Mount Kosciuszko is 2,228 metres high, and is the highest peak on the Australian mainland. At 6,900 sq kms, Kosciuszko National Park is the largest in New South Wales. In 1997 Kosciuszko National Park was given international significance by being declared a World Biosphere Reserve by UNESCO.ount Kosciuszko is 2,228 metres high, and is the highest peak on the Australian mainland. At 6,900 sq kms, Kosciuszko National Park is the largest in New South Wales. In 1997 Kosciuszko National Park was given international significance by being declared a World Biosphere Reserve by UNESCO.