The name for the waterway Ewey Bay first appears in an 1827 map by surveyor Robert Dixon.
As Dixon had labelled other localities around Port Hacking with Aboriginal names, it is assumed that Ewey was Dixon's recording of the Aboriginal name too.

Land in the area was released as the Village of Weerona in 1889.
The spelling Yowie first appears around the same time.

In an 1890 newspaper letter to the editor, Richard Hill claimed the meaning of Yowie was "Cooee".
Referring to Yowie Point, he claimed that there "the blacks, when travelling north, used to cooey to their friends on the north, and were brought over in the canoes..." The word “yowi” also appeared as “echo of a cooee” on a list of Aboriginal words collected in 1899 by the Anthropological Society of Australasia, in the Liverpool (police) district, which had earlier included the current Sutherland Shire area.
There appears to be no relationship to the mythical Australian creature called a Yowie.

It is however unclear why both Ewey and Yowie were in use.
According to one suggestion, Ewey might have been associated with ewes when sheep were run in the area in the 1860s.
Some of the workers with various accents might have pronounced “ewe” as “yow” and thus introduced the pronunciation Yowie.

As reported by local newspapers, the Sutherland Shire Council attempted to establish Ewey Bay as the correct name.
However, the suburb was officially assigned the name Yowie Bay in 1973 by the Geographical Names Board.
The name for the waterway Ewey Bay first appears in an 1827 map by surveyor Robert Dixon. As Dixon had labelled other localities around Port Hacking with Aboriginal names, it is assumed that Ewey was Dixon's recording of the Aboriginal name too. 
Land in the area was released as the Village of Weerona in 1889. The spelling Yowie first appears around the same time.
In an 1890 newspaper letter to the editor, Richard Hill claimed the meaning of Yowie was "Cooee". Referring to Yowie Point, he claimed that there "the blacks, when travelling north, used to cooey to their friends on the north, and were brought over in the canoes..." The word “yowi” also appeared as “echo of a cooee” on a list of Aboriginal words collected in 1899 by the Anthropological Society of Australasia, in the Liverpool (police) district, which had earlier included the current Sutherland Shire area. There appears to be no relationship to the mythical Australian creature called a Yowie.
It is however unclear why both Ewey and Yowie were in use. According to one suggestion, Ewey might have been associated with ewes when sheep were run in the area in the 1860s. Some of the workers with various accents might have pronounced “ewe” as “yow” and thus introduced the pronunciation Yowie. 
As reported by local newspapers, the Sutherland Shire Council attempted to establish Ewey Bay as the correct name. However, the suburb was officially assigned the name Yowie Bay in 1973 by the Geographical Names Board.
Yowie Bay, New South Wales