Mankind has had a long, tempestuous history with frontiers. We crave to encounter them, to push them, to exploit them. They often kill us, and yet we mourn them when they disappear. If you find yourself lamenting the death of the frontier, don't lose heart -- keep a candle burning! Not only is there the entire universe, but here on Earth there are still quite a few wildernesses through which humanity has barely traipsed. If you're looking for new wilderness to encounter or simply the reassurance that there still is some out there, then look no further than Popular Mechanics' 10 Greatest Wildernesses in the World.Are there other relatively untouched wildernesses you think ought to be on this list? Tell us why in comments section below.