Cleft Island, also known as Skull Rock, is a small, rugged, granite island in the Anser group of islands to the southwest of Wilsons Promontory, Victoria, Australia. The island lies within the Wilsons Promontory National Park.

Due to the position of the island, high winds and ancient waves have carved out a fascinating 130-meters wide, 60-meter-tall cave that sits in this hollowed-out cavern. The rugged formation can be seen from the coast, but it is only from up close on a boat that the island can truly be appreciated.

Little is known about the history of the island, but it is said that more people have been on the moon than inside Skull Rock. Due to the precarious cliffs and surrounding waves, the climb up the slippery rocks would be rather treacherous and local records suggest that only nine people have been inside the deep cavern.

In a recent expedition involving Neil Oliver, a Scottish television presenter, a team landed on the island by helicopter and abseiled down into the grassy cavern. They found old decaying cannonballs, which local historians believe was a result of passing ships using the rock formation as target practice over the years.

Until now, the mystery of Skull Rock — and venturing anywhere near the granite mountain — has posed as a challenge to anyone visiting ‘The Prom’ National Park.

According to the Internet