The trail begins on Willow Lake and winds through typical northern forests, consisting of alternating birch woods and spruce swamps. Most of the trail is flat to gently rolling hills. Most of the hills are around the Susitna River. The Yentna Station Checkpoint is located 18 miles upriver from the confluence of the Susitna and Yentna Rivers, at the Yentna Station Roadhouse, a long-time supporter and partner of the Iditarod that is also a wilderness lodge and bed & breakfast and a great place for spectators. Mushers pass through the Yentna Station Roadhouse checkpoint in a matter of hours due to being the first checkpoint off the road system! They will spread out from here.