Curtin University scientists have discovered that Hillarys is sinking because of increased demands on aquifer water supplies in the metropolitan area.

Over a five-year period between 2000-2005, the beachside suburb - famous for its boat harbour - sank six millimetres.

The Great Escape has been a long-time tenant of Hillarys Boat Harbour. Credit:Erin Jonasson

Professor of Geodesy, Will Featherstone, said that they had found a correlation between the land subsiding and water being drawn out of aquifers to meet Perth's water demand.

"As water is drawn out, the land begins to sink into the void that has been created," he said.