Bass Strait

Bass Strait is a significant maritime passage in Australia. It separates the island state of Tasmania from the Australian mainland. Specifically, it lies between the Victorian coast and northern Tasmania. This waterway serves as the most direct route between the Great Australian Bight and the Tasman Sea. It also provides the only maritime entry into the economically important Port Phillip Bay.

The formation of the strait is tied to massive changes in Earth's climate. During the last glacial period, sea levels were much lower than they are today. Approximately 40,000 years ago, Aboriginal people could walk from the mainland to Tasmania. They traveled across a wide prehistoric land bridge called the Bassian Plain. This plain connected the southern Victoria coastline to the northern Tasmanian shores.

As the glacial period ended, the world began to warm. This caused sea levels to rise through a process called marine transgression. Between 11,800 and 8,700 years ago, the rising water created a westward embayment. By about 8,000 years ago, the rising sea completely flooded the basin. This event officially formed Bass Strait and isolated Tasmania as an island. The central area features a shallow depression known as the Bass Basin.

European explorers arrived much later to map these waters. Captain Abel Tasman may have detected the strait in 1642. He was searching for a massive Southern Continent. In 1770, Captain James Cook sailed near the area. He was uncertain if the landmasses were connected. The strait is named after the English physician George Bass. He and Matthew Flinders sailed across the water in 1798 and 1799. In 1800, Governor John Hunter officially named the area "Bass's Straits."

The geography of the seabed is complex and varied. The Bass Basin sits in the center of the strait. It is surrounded by two underwater plateaus called sills. These are the Bassian Rise in the east and the King Island Rise in the west. These rises are made of Paleozoic granite. The Furneaux Islands sit on the Bassian Rise. The largest of these is Flinders Island. The King Island Rise includes King Island and the shallow Tail Bank.

Navigating Bass Strait has historically been very dangerous. The strait experiences powerful and wild storm waves. This happens because strong currents meet from the Indian Ocean and the Tasman Sea. Many ships were lost on the rocks and reefs during the 19th century. To improve safety, several lighthouses were built. A lighthouse was erected on Deal Island in 1848. The Cape Otway Lighthouse was also lit in 1848. Later, the Cape Wickham Lighthouse was lit in 1861.

Today, the strait is a major source of natural resources. Large oil and gas fields exist in the eastern Gippsland Basin. These fields were mostly discovered during the 1960s. For example, the Halibut Field was found in 1967. The Cobia Field was discovered in 1972. The Fortescue Field was found in 1978. These resources are often sent to processing facilities via pipelines.

These facilities are located in places like Longford and Geelong.

Environmental protection is also a key part of the region. There are over 50 islands located within the strait. Many of these islands have protected status. The Kent Group National Park covers the Kent Group islands. This park is contained within the Beagle Commonwealth Marine Reserve. There are also several Commonwealth marine reserves in the area. These efforts help manage the many different ecosystems found in these waters.