On 11 July 1810, Frederick Hasselborough discovered Macquarie Island, naming it after Lachlan Macquarie (the Governor of New South Wales). The island lies about halfway between Tasmania and the Antarctic continent, and is about 128 sq km in size. Its highest point is Mt Hamilton, which rises up to 433 m. In 1999, the ocean around Macquarie became an Australian Marine Park. Like almost every other sub-Antarctic island, Macquarie Island has no trees. However, it is the only island made only of rocks from deep within the earth's mantle and oceanic crust - 600,000 years ago it emerged from the sea and continues to rise at the rate of 0.8 mm each year (that's why earth quakes occur often on the island). Rats, mice, cats and rabbits (left behind by sealers) continue to destroy the island's wildlife today. In 1978, the myxoma virus was introduced to the island, and it has reduced the rabbit population by 93%. The cats, however, have been much more difficult to get rid of - the Australian government is spending AUS$ 9000 per cat to rid the island of its remaining 100 cats. Currently the island has a large population of elephant, New Zealand, Antarctic and Sub-Antarctic seals. There are also many Royal, Gentoo, King and Rockhopper penguins and several species of albatrosses.