The 26th parallel south latitude is a circle of latitude that is 26 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America.
26th parallel south Wikipedia
Starting at the Prime Meridian and heading eastwards, the parallel 26° south passes through:
In Australia, the northernmost border of South Australia, and the southernmost border of the Northern Territory are defined by 26° south.
Additionally, 26° south also defines an approximately 127 metre section of the Western Australia/Northern Territory border at Surveyor Generals Corner due to inaccuracies in the 1920s for fixing positions under constraints of available technology.
The parallel also defines part of the Queensland and South Australia border between the 138th and 141st meridians east.