This photograph would have been taken not too far from LeoDaVinci's (above), but many years earlier; from memory, sometime in mid 1980's.
It's London Bridge, a rock formation accessible from the Great Ocean Road. The sea that day was unusually calm.
In 1990, the centre span of London Bridge collapsed into the water, leaving some sight-seers isolated on the seaward section. A rather exciting helicopter rescue ensued!