Dangerous Reef
reef in Australia
Dangerous Reef is an island and reef system located in the Spencer Gulf in the Australian state of South Australia about 32.5 kilometres (20.2 mi) east-southeast of the city, Port Lincoln. It is the southernmost member of the Sir Joseph Banks Group. It has been the site of a navigation aid since 1911. It is notable as the site of a breeding colony of Australian sea lions. The waters adjoining its shore are notable as a place to view great white sharks to the extent that it was both a popular gamefishing and shark cage diving venue during the twentieth century, and was used to film footage for Blue Water White Death and Jaws. The island has enjoyed protected area status since 1900 and it has been part of the Sir Joseph Banks Group Conservation Park since 1989.
Description
Dangerous Reef is located in Spencer Gulf about 32.5 kilometres (20.2 mi) east-south east of the city of Port Lincoln, about 17 kilometres (9 nmi) north-northeast of Observatory Point on the northeast coast of Thistle Island and is about 17.5 kilometres (10.9 mi) east of the nearest point of the mainland on the Eyre Peninsula.
Officially, it is described in one source as being a "reef." In another official source, it is considered to be an island as it is listed as being part of the island group known as the Sir Joseph Banks Group despite being located about 15.5 kilometres (9.6 mi) south-southwest of Stickney Island, the nearest group member.
Dangerous Reef itself is described as consisting of "a chain of four large rocks" with the tallest reaching a height of 3 metres (9.8 ft) with the remainder being "barely dry" at low tide as well as some other "small rocks." At high tide, the island/reef system has an area of dry land covering about 12 hectares (30 acres) while at low tide, the system dries to an area of about 40 hectares (100 acres). Access to the island/reef system which is subject to permission by the responsible government agency due to the island group's protected area status (refer below) is either via boat or helicopter.
Begin with the source’s own compact description: “Dangerous Reef” is reef in Australia. The dossier treats that line as a proposition to test through Dangerous, Reef and reef, not as a finished interpretation.
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The phrase “reef in Australia” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Jul 13, 2026. The linked authority identifier is Q21896737. Authority coordinates are -34.817, 136.229. None of the 1 selected statements returned an explicit reference. The first chronological checks are 1911, 1900 and 1989.
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This entry incorporates text from “Dangerous Reef” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.