Cocklebiddy is a small roadhouse community located on the Eyre Highway in Western Australia. It is the third stop east of Norseman on the long journey east across the Nullarbor Plain. The area is noted for its underground caves and lakes.
Cocklebiddy started as an Aboriginal mission station, of which only the stone foundations remain today. The area at one stage was thought to be a potential water source and during World War II, Army engineers attempted to tap fresh water from the lakes, but it was found that a thin skin of fresh water overlay a vast volume of saline water.
The Eyre telegraph station operated south of the settlement from 1897 until 1929. Unlike most others, it remained in a relatively well-preserved state due to its isolation and protection from the Southern Ocean, and in 1976, when the State Government created the Nuytsland Nature Reserve, the facility was converted into a wildlife observatory, which opened in 1978.
Like other locations in the Nullarbor Plain area, the area consists of nothing more than a roadhouse. The Cocklebiddy area is noted for its underground caves, the most notable of which is Cocklebiddy cave – a single passage more than 6 km long, of which around 90% is underwater and only accessible via cave diving. In 1983, a French team set a world record here for the longest cave dive in the world, which was beaten in 1995 by an Australian, Christopher Brown who went 20 m further.
49 kilometres (30 mi) south of the roadhouse is the Eyre Bird Observatory, near the old Eyre Telegraph station, which offers basic camping facilities. Over 230 species of birds have been spotted there.