The Neptune Islands, both the two North Neptune and two South Neptune islands (as well as the Low Rocks), are at the mouth of the Spencer Gulf on the south coast of Australia. They were first seen by Europeans in 1802 and called "Neptune’s Isles" due to their seeming inaccessibility to humans. There is little known about any Aboriginal heritage on the islands and two Native Title claims made in the 1990s did not include the islands.
There is a lighthouse on South Neptune Island, lit in 1901. When it was automated in 1990, the keepers and their families left the island. The South Neptune Lighthouse Complex now is listed on the South Australia Heritage Register. The low profile of the islands, wind exposure and salt spray severely limit what grows on the islands. Guano was mined there until 1919 and there is fishing outside the marine reserve for species such as abalone. Little penguins, which used to abound on the islands, were determined to be extirpated by 2006. Other bird species still nest on the islands.
The Neptune Islands are best known for their cage diving with great white sharks, some of which are enormous (such as Joan of Shark, who was measured at 17’8” when tagged). This is the only area in Australia where one can cage dive with these animals. The sharks are there for the sea lion and fur seal colonies. The area is currently protected as a terrestrial and marine conservation area managed by the Neptune Islands Group (Ron and Valerie Taylor) Marine Park.