Whilst all publically accessible land is available with appropriate permission there are currently 4 locations in Western Australia, where geocaching is restricted, with some locations banned totally.
Some of these areas require permission prior to placement so it's always best to check first
If you plan to place a cache in any of these area,
- Rottnest Island
- Kings Park
- Bold Park
- Stirling City Council Local Government Area
- Melville City Council parks and reserves
Then make sure you read the following link
The full rules/guidelines for these areas can be found here along with links to the relevant authorities to gain any required permission.