Thought there were just eight of the Twelve Apostles still standing off the Great Ocean Road coastline? Think again.

Scientists have found a further five limestone stacks underwater, in a surprise discovery which probably makes the marine monoliths the world's only known limestone columns to remain preserved in the ocean.

The sea stacks, which appear to host a variety of coral and other sea life, are located in a linear formation six kilometres offshore, between Point Campbell and Peterborough.