O'Sullivan Beach is a seaside suburb in the southern Adelaide metropolitan area, within the City of Onkaparinga.

The very first development to occur along the coast of O'Sullivan Beach can be traced back to pre-colonization times, almost 40,000 years ago.

The Aboriginal Kaurna people used the coastal area of O'Sullivan Beach as a place for seasonal residence.

An area of surveyed land covering Glenelg to Witton Bluff (Christies Beach) known as District B, was made available for settlement in 1838.

The reef covers a 5 hectare area and has been seeded with young Ostrea angasi, a native flat oyster species.

The reef is expected to improve ambient water quality and provide habitat for a variety of marine species.