The only active volcano in Australian territory, erupting under glaciers on one of Earth's most remote islands. Lava and ice interact in ways studied nowhere else.
Tristannew (original) Derivative: SHB2000 (cropped), CC BY-SA 4.0, via Wikimedia Commons
A fire beneath the ice
On Heard Island, one of the most remote places on Earth, Australia's only active volcano is constantly erupting. The peak, named Mawson Peak, is the summit of a massive volcanic structure called Big Ben and reaches an elevation of 2,745 meters (9,006 feet). This makes it taller than any mountain on the Australian mainland. Located approximately 4,000 kilometers southwest of Perth, the island is a territory of Australia and is almost entirely uninhabited.
Mawson Peak is a stratovolcano that has been growing for at least the last one million years. Around 70 percent of the island is covered by glaciers, with some ice cliffs reaching heights of 30 meters. The volcano itself is covered by an extensive ice cap, meaning that many of its frequent eruptions occur directly beneath the ice. This creates a rare natural laboratory for studying glaciovolcanic interactions, the complex processes that occur when molten rock meets frozen water. The volcano's lava is primarily alkali basalt, and it has a low average magma discharge rate of about 200,000 cubic meters per year.
A laboratory for planetary science
The continuous activity of Mawson Peak shows geological processes. Eruptions, observed regularly since the mid-20th century and confirmed by satellite data in recent years, send lava flows down the glacier-covered flanks. One eruption in February 2026 produced an ash plume that rose to an altitude of 7.3 kilometers. When lava flows under or over the thick ice, it can form subglacial tunnels, meltwater lakes, and trigger glacial outburst floods. This interaction is of great interest to planetary scientists, as similar processes are thought to occur on ice-covered worlds like Mars.
The island and its surrounding waters were declared a UNESCO World Heritage site in 1997, recognizing its geology and pristine ecosystem. As a protected wilderness, it has virtually no alien species, showing an undisturbed sub-Antarctic environment. The glaciers on Heard Island are also retreating rapidly, providing scientists with an unparalleled opportunity to study how plants and animals colonize newly de-glaciated land. The volcanic activity affects the marine ecosystem by releasing iron into the Southern Ocean, which can stimulate phytoplankton growth up to 500 kilometers away.
💡Fun Facts
Mawson Peak is named after Sir Douglas Mawson, the famed Australian geologist and Antarctic explorer who visited the island in 1929.
The first confirmed ascent to the summit of Mawson Peak was accomplished in 1965 by an expedition led by Major Warwick Deacock.
The nearby McDonald Islands, part of the same territory, reawakened in the 1990s after 75,000 years of dormancy, more than doubling the main island's size.
Heard Island is a critical breeding ground for millions of penguins, including King, Gentoo, and Macaroni species, as well as several species of seals and albatrosses.
Access is restricted to scientific expeditions with a permit from the Australian Antarctic Division.
Admission
Not applicable. Tourism is extremely limited and managed under strict permit conditions.
Accessibility
The island is uninhabited and one of the most remote places on Earth. There are no ports or airstrips. Access is via a multi-week sea voyage through the Southern Ocean. All travel on the island is by foot.
