What neighboring suburb of O'Halloran Hill has a population of more than 12,000 people?
O'Halloran Hill, South Australia:  The suburb is split between the Cities of Marion and Onkaparinga, and it neighbours Happy Valley, Hallett Cove, Trott Park and Darlington. Hallett Cove, South Australia: Hallett Cove is a coastal suburb in the south of Adelaide, South Australia, with a population of more than 12,000 people.
Hallett Cove