This one is close to the start ot the Dianella Track. One of the many walking tracks that take you up to the top of Castle Hill. You will find three more caches along this track, before it joins the road which takes you the last few hundedred metres to the top.
You can look for the cache before you start making your way up, or you can leave it as a reward at the end, when you come back down 
It is a rather small container, logbook only, so I hope you have a pen in your car.
You might, or might not have to stretch to retrieve it 
And afterwards have fun on the rest of the track!