not really into Manhwa but i'm so desperate to read something i guess i'll read it
That one's been in my "to read later" pile for quite a while, but it's just that I haven't gotten to it yet, it came highly recommended to me and it was for just that sort of reason, all the outdoors, life and death kind of stuff (mountain climbing/survival as I remember).
Good luck
speaking of which, nobody mentioned Assassination Classroom, it's kind of got survival type themes to it...........though it's shounen and pretty popular, so you probably already know about it.
http://vatoto.com/comic/_/comics/assassination-classroom-r5411
And the only other thing that comes to mind is another webtoon called Afterschool War Activities, though it's scanlation has really just started..................but it's very popular on Naver, it's supposed to be quite bloody and terrifying with the whole theme being survival.
http://vatoto.com/comic/_/comics/afterschool-war-activities-r8789