Re: Most dangerous trek in the world?
I've done a good bit of hiking in South Korea and northeastern China. It's beautiful country, but man, you know that if you get hurt, you're going to die. There's no hospital for a LONG way, and there isn't anyone who gives a shit about a Waiguoren (foreigner) to get him some help.
My favorite place is Changbaishan (or Bekdusan if you're Korean). It straddles the Chinese-North Korean border in Manchuria. The mountain is just a dormant volcano that is the mythical birthplace of the Korean people. The climb isn't that bad, but the vista if un-fucking-believable. One of the few places in China that I'd go back to. Here are a few pics, though I didn't take these as I lacked a digital camera in 2004.
This pic is of the ascent from the Chinese side. You walk right next to the falls as the water's coming from the lake in the middle of the crater separating China from North Korea.
This pic is from the Chinese side facing the North Korean side. And if you're curious, I didn't see any fence keeping you from just walking over to NK. Don't know why anyone would want to go to that godforsaken hell hole, but it didn't look like there was anything to stop you.