Back in the '70s, I used to run as far as Iron Creek. Had a 22ft narrow Monark I could cartop carry and pushed it with a 25 Hp Johnson with jet, one of the first jet units in Alaska. Disappointment Creek was always a challenge, but worth it. Water beyond Iron Creek is nothing but rapids as the gorge gets pretty tight. Steve Mahay did run the canyon as great publicity for his big inboard jet.