Some 2700 ha formed the core of the reserve when it was originally proclaimed as Gum Lagoon National Park in August 1970.

[4] The conservation park is located on land in the gazetted localities of Laffer, Petherick and Tilley Swamp.

[5] It contains ranges of calcarenite dunes and interdunal flats, with slow-moving surface water drainage systems and blocks of remnant vegetation.

The main feature of the conservation park is the Duck Island Watercourse which runs along a wide interdunal flat studded with ephemeral swamps and isolated sandhills.

[7] The conservation park's vegetation includes Banksia ornata shrubland, Melaleuca brevifolia low shrubland, Eucalyptus arenacea open woodland and Eucalyptus diversifolia open mallee, while the wetter areas are characterised by red gum woodland and aquatic herblands.