I visited here while on a two-week bus tour. Very few of us made the trek to Avalanche Falls. A few started but turned back. There are some steep climbs on gravel and steps that are slippery when wet. It took me about 75 minutes which the pamphlet gives as the approximate time. I enjoyed it.
The falls are part of the Flume Gorge trail along wooden walkways and bridges through the gorge. The access walks and bridges feel very sturdy and secure. Spring time or after a heavy rain is the best time to visit, but it's beautiful regardless. Not much room for tripods, but you can rest your camera on the wide railings for...
This is near the flume gorge and it is near the top of many stairs; easily accessible if you are relatively fit. Lovely views of the water - you can take nice videos following the water all the way down as far as you can see.