Yes - I was absorbed by the flooded view of Oneonta, too! But the main trip was down Henline Creek, if you're wondering where they were. The hike to Henline Falls (where the segment ends) is a nice trip if you're in the Opal Creek area.
There are other waterfalls upstream, but strictly for bushwhackers - these guys are among several canyoneers that stumbled across
my various web accounts of the area. But the original explorer of the upper canyon was Maynard Drawson some 35 years ago, before canyoneering was even invented! He gave me permission to post his original narrative on the above link, and it's a fun read.
Tom