Although this is a virtual cache, it won't be easy to get to. In fact, not much in Mongolia is easy to get to, hence the terrain rating for this cache.
You'll need to drive about a day south of Khovd in western Mongolia to reach the Blue Caves site. There's no real road to the cave site from Khovd, so your GPS will definitely come in handy to find the site while following a coarse dirt track. There are two separate caves at this location and they are located a good hike above the dirt track.
The larger of the caves features some very impressive ancient drawings in a series of chambers within the cave (see picture); however the drawings have had some damage to them in recent years. The second, and smaller cave does not contain any drawings.
Onto the virtual cache: to score a find for this cache, take your GPS as close to the entrance of the larger cave (without losing the signal) and have a friend take a picture of yourself with your GPS and with the cavern of the cave behind you and upload it with your find. Any additional pictures are also welcome of the drawings within the larger cave or of your adventures enroute to the cache site.