Whilst watching the "Lake Eyre" show on the ABC earlier this month, I became aware of a region in the Australia that's called "The Painted Hills". Unfortunately it's on private land and currently the only way to see it is via plane flights over the top (with permission of the land owners). There are no helicopter flights over or in/out or other means of easy access (I've asked).
In terms of access at ground level, my estimates from current research are that it is approximately an 8km trek (3 to 4 hr walk) over the outback from the nearest "road" to the boarder of an area that's about 20km x 10km. But that's just it - I'm guesstimating because the exact location is secret. But now that it's a known feature, the secret will only last until someone uploads the flight path from a GPS and/or GPS coordinates from a GPS enabled phone/camera when they go "snap".
In terms of photographic potential it's an unknown. As far as I can tell, all of the photographs I can find on the Internet are from planes. Similarly I have no idea about which regions inside that 200km2 area are good/bad.
I'm wondering if there are others, either local or abroad, who would be interested in writing to the owners and seeking permission to travel and shoot there. I'm hoping that if I can find a group of interested people then I've got a better chance of success than trying to do it solo.
Update: further research shows the area in question to be within the Woomera Protected Area (weapons testing) zoned "Infrequent Use". It is thus necessary to contact the relevant government offices to see what the protocol is for people looking to venture in and take photographs. The current paperwork is focused on supporting companies doing mineral exploration, which is not exactly a good fit.