This isn't a driveby. This an overnight hike in one of Victoria's most remote areas, with no water at all, so you'll need all the proper gear and preparation. This cache is not recommended in the warmer months.
Preparation
There are a number of things you will need in order to prepare for this cache. Some things are absolutely essential, other things are just a really good idea.
The first thing you must do is fill out a trip intention form. This lets the rangers know where you are going to be. It's not entirely their job to make sure you're safe, but if you disappear into the wilderness and get lost they need to know where to start looking. Download the form at www.parkweb.vic.gov.au/__data/assets/pdf_file/0006/564873/Wyperfeld_group-trip-intention-form.pdf. Fill the form out, specifying the hike from the Murrayville Track to Messa Rocks and back, and specifying your camping intentions, and email it back to Parks Victoria (info@parks.vic.gov.au), or telephone the ranger at Rainbow (03) 5395 1345.
While you're on the Internet, check the DELWP website (http://delwp.vic.gov.au/) for warnings, bushfires, planned burns, and other incidents in the area, the CFA website (http://www.cfa.vic.gov.au/) for similar fire-related information and the BoM site (http://www.bom.gov.au/) for the local weather forecast. Please, avoid hiking in hot weather.
The total length of the hike is about 30 km, and it's through deep sand in places, so unless you're Vladimir Putin or some other super human, it's an overnighter. You must bring full camping stuff and food and especially water. Fires are discouraged here, so you'll need either to only bring cold food or bring your own camping stove.
The other thing you must bring is a compass. The hike is probably longer than your GPSr is going to last on normal batteries (Skogpingvin's GPSr certainly couldn't go the distance), so use the GPSr only once or twice to make sure your compass is guiding you correctly. Part of this trek is off track in the wilderness, and every minute you use your GPSr for navigation is a minute closer to that nasty point when you realise your batteries are going to run out before you get back to the track, and you're screwed. A magnetic compass (not your phone) might be the only thing that keeps you alive. No, I'm serious. Get old school, bring a compass, but before you go, learn how to use it in undulating country where you can't see the horizon.
You'll also probably want to bring gaiters. Not only is this Brown Snake country, but bush bashing with bare legs is only going to get you into a heap of trouble.
It's also a good idea to bring a personal locator beacon, so if you do get snake bite, or break a leg, you can call a rescue helicopter. You can get one for about $300 these days, and registered with the Australian Maritime Safety Authority they're the best insurance around. Take it from Skogpingvin, your family (for Skogpingvin, that's the HenGuin and The Chick) will appreciate you having it.
The hike in
Broken Bucket, about 22 km north of Yanac, and about a 7 hour drive from Melbourne, is a good place to camp the night and get a good early start. There's a drop toilet and bore water here.
The trip starts at the Messa Track junction on the Murrayville Track. Murrayville Track is navigable with a 2WD if the weather is good. However, when it rains significantly the surface becomes impassible, even with a 4WD. Messa Track West starts from a point about 41 km north of Broken Bucket, or 2 km south of Milmed Rock Track. There's a sign here that says management vehicles and walkers only. Under no circumstances take your car in the track - not only is it illegal, but the track was closed many years ago and it's overgrown significantly, very sandy and you'll probably just get stuck. There's no actual car park here, but you can probably find somewhere responsible to leave it nearby.
From here it's a 10.3 km walk through sand which is soft in places to a fork in the trail. Take the left fork, and follow it to the end, which is another 2.9 km. You can camp here, it's a spot called Messa Rocks. The cave is just large enough to crawl into, but you wouldn't want to sleep in it, unless you're desperate and don't mind feral bees. it was formed as the softer lower levels were eroded from under a slightly harder metamorphic sandstone. If you look closely you'll see harder marble-like pebbles trapped in the sandstone. Please do not disturb or damage the cave, and do not disturb the ground.
There are some Parks Victoria requirements about camping and the area in general. Fires are discouraged here (and absolutely prohibited on days of total fire bans) but if you need one for cooking, it must be kept small for safety and to conserve the local environment. All rubbish has to be brought back to the car. Only leave footprints. Because this is a wilderness area, if signs of usage begin to appear, especially if tracks start appearing around the area, the cache may have to be closed.
While you're camping, listen out at night for the call of the Australian Spotted Nightjar, one of the weirdest sounds you'll hear. Look up as well - when there's no moon, the skies here are about as dark as they get anywhere on the planet, so you'll see great stars and the Milky Way. On the trail back, in particular in the Cypress Pines, look out for Gilbert's Whistlers, or maybe even a Red-lored Whistler. If you do see a Red-Lored Whistler, you'll be one of few people in Victoria to have done so.
The hike to the cache
From the camping spot, it's 1.6 km due south to GZ. There are no tracks in this area, and bush bashing is slow going - it'll take you up to three hours to reach GZ and get back. This is where you're going to need both your compass navigation skills, and the occasional GPS confirmation. Parks Victoria advises that there are iron deposits in the area, which may upset magnetic compasses. Skogpingvin didn't have any problems, but a GPS fix every half hour would be wise, and not too much drain on the batteries.
While you're on this part of the hike, stop occasionally and think about what's around you. Listen to the silence, breathe the air, and remember just how much the desert is going to care if you get lost or break a leg.
The cache itself is not hidden. It's an ammo box under a brush bush at a high point of one of the mesas, and the clearing even shows up on the Bing Maps satellite photo. You won't have to dig anything or disturb the landscape in any way. The box has a swap or two in it, plus a good sized log, as well as a couple of spare ziploc bags. It should last a few years.
Once you've securely closed the cache and put it back under the bush, you'll have to retrace your steps back to Messa Rocks. This is due north, and is recognisable from a reasonable distance.
Lastly, Parks Victoria want to monitor the traffic to this cache, so please remember to log your visit, including any DNFs.
The first-to-find prize is penguin related, like our other caches.