Mornington covers more than 3,216 km2, making it Australia’s largest non-government protected area. The property covers 4.2% of the Central Kimberley Bioregion and 7.3% of the Pentecost subregion.
Mornington is surrounded by active cattle properties and areas of vacant crown land. It is therefore strategically positioned to act as a catalyst for landscape-scale conservation efforts. The sanctuary contains much of the upper catchment of the Fitzroy River, one of the most important river systems in northern Australia. The Fitzroy has the highest diversity of freshwater fish in Western Australia. It also contains significant riparian habitats along the Hann, Traine and Adcock Rivers.