Lake Nunijup is an ephemeral salt lake located in the Great Southern region of Western Australia, approximately 27 km (17 mi) south west of Cranbrook and 41 km (25 mi) north west of Mount Barker.

The surrounding landscape is composed of lakes and swamps with lunettes situated over tertiary alluvium, colluvium and sand with underlying laterite also present.

Small amounts of brackish water can be received from the south western flanks of the Stirling Range that can flow into the lake.

[4] The traditional owners of the area are the Noongar peoples, who have inhabited the region for tens of thousands of years.

[3] Around the lake the overstorey is dominated by Eucalyptus wandoo while the mid-storey contains Melaleuca cuticularis with a sparse understorey of Baumea juncea.