Heard Island and McDonald Islands (HIMI) are remote, uninhabited volcanic islands located in the southern Indian Ocean, about two-thirds of the way from Madagascar to Antarctica. They are territories of Australia and represent some of the most pristine environments on Earth, largely untouched by human activity. Discovered in the mid-19th century—Heard Island by Peter Heard in 1853 and the McDonald Islands a few years later—the islands were initially exploited in the late 19th century for seal hunting, which quickly depleted local populations. In 1947, Australia formally claimed sovereignty over the islands, incorporating them as an external territory in 1953. Today, Heard Island is notable for its active volcano, Mawson Peak, which stands as Australia’s highest mountain outside its mainland. The islands hold immense scientific value, supporting diverse biological communities and providing unique opportunities for research into natural processes largely uninfluenced by humans. In recognition of their ecological significance, they were inscribed as a UNESCO World Heritage Site in 1997.