Exploring Australia's Habitable Islands: A Comprehensive Guide (2025)

Australia is home to 8,222 islands, each with its own unique ecosystem. These islands are scattered across the Pacific, Indian, and Southern Oceans, as well as the Coral and Timor Seas, and range from small rocks barely breaking the surface to islands over twice the size of the Australian Capital Territory. With such a diverse range of habitats, these islands play a crucial role in conserving Australia's wildlife. By eradicating feral cats, which are present on 99.8% of the Australian mainland, several islands have become safe havens for endangered species, allowing them to recover and thrive.

Australia's unique islands: 8,222 in total

Australia has 8,222 islands within its maritime borders. Each of these islands is completely unique, with its own precious ecosystem where plants and animals interact in a delicate balance. These islands range from small rocks that are not covered by water at high tide to islands that are more than twice the size of the Australian Capital Territory.

Among Australia's islands is the world's largest sand island, K'gari, which stretches over 123 kilometres in length and reaches 25 kilometres at its widest point. K'gari displays vastly different landscapes, ranging from freshwater lakes to sand dunes, wetlands, crystal-clear lakes, and dense rainforests. The island is also famous for its coloured sands, which have been stained by decayed vegetation leaching into the sand for thousands of years.

Another notable island in Australia is Macquarie Island, which was nominated by the Australian Government for inscription on the World Heritage Register in 1996 due to its unique geological features. Macquarie Island is the only place on Earth where rocks from the Earth's mantle are exposed above sea level, including excellent examples of pillow basalts and other extrusive rocks.

Many of Australia's islands provide a safe haven for threatened species, as they are free from invasive species such as feral cats. These islands play a crucial role in securing a future for many mainland animals, such as quolls, bettongs, and pademelons, which have sought refuge from predators like foxes and cats.

K'gari, the world's largest sand island

Australia has 8,222 islands within its maritime borders. One of these islands is K'gari, formerly known as Fraser Island, which is the world's largest sand island. Located off the coast of southern Queensland, K'gari stretches over 123 kilometres in length and 22 to 25 kilometres at its widest point. The island is about 1,840 square kilometres or 710 square miles in area.

K'gari is home to a diverse range of landscapes, including freshwater lakes, sand dunes, wetlands, crystal-clear lakes, dense rainforests, eucalyptus woodland, mangrove forests, wallum, peat swamps, and coastal heaths. The island is also known for its coloured sands, which have been stained by decayed vegetation leaching into the sand for thousands of years. Some deposits are up to eight million years old. The sand dunes on the island move at a rate of 1 to 2 metres per year due to year-round winds from the southeast and grow to a height of 244 metres.

The island is part of the traditional lands of the Butchulla people, who named it "K'gari", meaning "a beautiful white spirit". According to the Butchulla people, "She is beautiful to us—she is our mother. She provides food, water, and shelter, and in return, we protect and preserve her." In 2021, the World Heritage Area within Great Sandy National Park and the surrounding waters were officially renamed "K'gari (Fraser Island)" in recognition of the Butchulla name.

K'gari is a popular destination for outdoor adventures, offering some of the best four-wheel driving experiences in the country. The island and its fellow sand islands near Brisbane provide unique natural landscapes and attractions, including tall rainforests, freshwater lakes, and whale-watching opportunities.

Tasmania: Australia's most populous island

Australia has 8,222 islands within its maritime borders. The largest of these is Tasmania, which has an area of 64,519 square kilometres and a population of 570,000 people. Tasmania is home to a diverse range of plant and animal life, including quolls, bettongs, and pademelons. The island has a rich history and culture, with a strong focus on environmental conservation.

Tasmania's remote location has helped to shape its unique character and natural environment. The island has a temperate climate, with cool, wet winters and warm, dry summers. This climate supports a range of outdoor activities, such as hiking and camping, which are popular with both locals and tourists. The famous Overland Track is a 65-kilometre multi-day hike that showcases the island's stunning natural scenery, including its rugged mountains, pristine lakes, and wild rivers.

Tasmania has a strong environmental record and is known for its commitment to conservation and sustainability. The island has a number of national parks and protected areas, including the famous Cradle Mountain-Lake St. Clair National Park, which is home to an abundance of native wildlife and unique plant species. The Tasmanian government and local communities work together to protect the island's fragile ecosystem and preserve its natural beauty for future generations.

In addition to its natural attractions, Tasmania also boasts a rich cultural heritage. The island has a long and fascinating history, with evidence of indigenous habitation dating back thousands of years. European settlement began in the early 19th century, and Tasmania became a separate colony from New South Wales in 1825. Today, Tasmania is a thriving centre of art, culture, and cuisine, with a vibrant festival scene and a growing reputation for its local produce and gourmet food and wine experiences.

Tasmania's remote location and unique environment have also presented some challenges, particularly in terms of infrastructure and accessibility. The Bass Strait, which separates Tasmania from the Australian mainland, has long been a barrier to travel and trade. However, the introduction of the Spirit of Tasmania ferry service in 1998 helped to improve transport links and boost the local economy. Today, Tasmania is a popular tourist destination, known for its stunning natural beauty, friendly locals, and abundant outdoor activities.

Feral-free islands: safe havens for threatened species

Australia has 8,222 islands within its maritime borders, ranging from small rocks barely poking above the waterline to islands larger than 1,000 square kilometres. These islands are a vital part of Australia's biodiversity and have been used as safe havens for threatened species.

Islands free from feral cats and other invasive species become safe havens for threatened species, reducing the problems associated with parasites spread by feral cats, which can affect health and agricultural productivity. Feral cats are the single greatest threat to Australia's native mammals, contributing to the extinction of over 20 mammal species since their introduction. They threaten around a third of the country's vulnerable mammals, reptiles, frogs, and birds.

Feral-free islands allow existing populations of threatened species to recover and carefully facilitate species reintroductions. In 2017, Australia had 101 island refuges, housing 38 different threatened mammals. These havens are especially effective for smaller, more vulnerable mammals, which are easy prey for introduced predators like cats and foxes. Populations of threatened species inside these havens have soared by an average of 680% over a 17-year period, while outside populations declined by an average of 63%.

However, maintaining these safe havens is challenging and expensive. They require ongoing human input to keep out feral predators, and when funding runs out, havens can fall into disrepair. Furthermore, while havens are effective in the short term, they are not a permanent solution. Animals reintroduced to the wild outside these havens often quickly fall prey to feral cats and foxes, highlighting the need for ongoing management and innovation in controlling feral predators.

Islands with human populations

Australia has 8,222 islands within its maritime borders. Out of these islands, only nine are larger than 390 square miles. Here is a list of some of the Australian islands with human populations:

Tasmania

Tasmania is the country's largest island and is also a state of Australia. It has a population of 570,000. The main island of Tasmania, which includes 94% of the state's land area, does not have a defined name but is sometimes referred to as the "Tasmanian mainland". There are 334 islands (or islets) within the state of Tasmania.

Melville Island

Melville Island, also referred to as Yermainer, is the second-biggest Australian island, occupying an area of about 2,234 square miles. It is located in the Timor Sea, off the coast of the Northern Territory. The largest settlement on Melville Island is Milikapiti, which is inhabited by over 559 people, followed by Pirlangimpi (440 people). Together with Bathurst and nine other uninhabited islands, Melville Island is referred to as the Tiwi Islands.

Kangaroo Island

Kangaroo Island is the third-biggest Australian island and is situated in South Australia, about 8.4 miles from Adelaide. It covers an area of 4,416 square kilometres (1,705 square miles).

Groote Eylandt

Groote Eylandt is the fourth-biggest Australian island and the largest in the Carpentaria Gulf, occupying an area of about 882 square miles. The island is 390 miles from Darwin and 31 miles from the Northern Territory. It is owned by the Warnindhilyagwa people.

K'gari

K'gari, also known as Fraser Island, is the world's largest sand island, located just off the coast of southern Queensland. It stretches over 123 kilometres in length and reaches 25 kilometres at its widest point. K'gari has a population large enough to include a World Heritage listing and the Great Sandy National Park, which covers 52,400 hectares on the northern half of the island.

Bribie Island

Bribie Island is located near Brisbane and has a population of 18,000.

Phillip Island

Phillip Island is located near Melbourne and has a population of 14,000.

Macquarie Island

Macquarie Island is located in the Tasman Sea and is the only place on Earth where rocks from the Earth's mantle are exposed above sea level. Australia has operated a research and Antarctic support station at the northern end of the island since 1948. The station is home to more than 40 people during the summer and around 20 people during the winter.

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