Portal entrance is surrounded by many elementals (Astyrrians, Avalanches, Blizzards, Scintillas, and Statics). Killing the Diamond Golem Suzerain at the bottom will open a temporary portal to the valley where Gaerlan's Citadel crashed (58.2N 47.9E). The golem with not respawn for one (??) hour, if you need to get back, there are portals in a bunker in Eastham that you will be flagged to use for one (??) hour.