Even at the put-in near Dalton Post, Yukon Territory, the Tat is a large river by lower-48 standards.  By the time the Alsek reaches the Pacific, it is second only to the Columbia River in the volume of water it contributes to the Pacific Ocean in the Western Hemisphere.  A typical Alsek flow is 100,000 cfs, which is about 10 times the flow of the Colorado through Grand Canyon.

  The Tat-Alsek is not a trip you do for big rapids.  You come here for pristine wilderness, hugh vistas, solitude, a glimpse at the last ice age, and wild life galore—brown and black bears, Dall sheep, mountain goats, wolves, all sorts of smaller critters, and more bald eagles that you can count.