Happy

From the upper put-in at Sheep Lake the Happy is fast, fun, clear, and beautiful, checking all the boxes for a great Alaska fly-in float trip. At low water in the summer or fall it's a nonstop mix of class 2/3 read & run rapids, with very few pools or slower sections. Medium or higher flows it would approach class 4-.

A slightly cheaper fly-in option would be a float plane to Puntilla lake followed by an 11 mile hike over the mountains to put in on Puntilla Creek.

There is a take-out option by floating 11 miles down the Skwentna and hiking out 1.2 miles to Finger Lake and organizing a float plane from there. The bushwhack is not easy. Steep, full of prickly plants, and once you reach the top of the canyon it's an ankle deep marsh and thick with bugs.

As of September 2020 there was a full-river sweeper a few miles from the put-in at Sheep Lake, around a blind corner in a narrow wooded section.  At higher flows could easily be deadly, but there is a small eddy just above it.

The folks at Winter Lake Lodge on Finger Lake run heli-assisted rafting trips on the lower section of the Happy, and could maybe provide flow information. Or try the pilots at Hood Lake in Anchorage.

Embick in Fast & Cold recommends continuing down the Skwentna another 40 miles flying out from the airstrip at Skwenta Village.