And apart from the awesome bunkers, there are also the colonial atmosphere & the furken quokkas! Very cute.
Here's a small selection of the pix I took (with my crappy 8mp camera) the last time I was there 2 years ago....
1. Number 1 gun (restored). Note the perspex cover inside the barrel to keep wildlife out.

2. Another view of Number 1 gun.

3. The breech inside the 'gunhouse'.

4. Remains of the former railway that carried ammo & other supplies to the Oliver Hill battery.

5. The entry to the magazine, engine rooms & tunnels.

6. One of the many rooms leading off the tunnels (selfy).

7. The highlight of this Island, the Quokkas...

Interestingly this island got it's name from these critters. The first people who landed here (the Dutch) thought they were giant rats. So they named it Rottnest which translates to Ratsnest in English. Gotta love those crazy pot smoking Dutch.
I have heaps more pix from there, I just put up a few as a teaser.
Enjoy.