One place I love is the Ape Canyon Trail up on Mt. St. Helens. It is considered one of the great rides in America. It's a trail that starts in old growth 'pre-eruption' forest meandering it's way up along the Lahar. The severely eroded riverbed carved from one of largest flash snow melts recorded in human history. This is a whole 'nother' story but it also created Lava Canyon, instantly.
So this view is from up above on Loowit trail, but this is the Lahar. On the near ridge on the right is the old growth forest the trail traverses through. It's a good climb, and is fairly unrelenting all the way up. It is very popular trail and one must be respectful of fellow trail users.
The mountain from the south. Ape Canyon trail going up.
At the top of the forest the trail opens up into the blast area. There are no trees remaining up here except those that have grown since the blast. It's a very special environment and unique on earth as there are no other recently erupted volcanoes in the Pacific Northwest.
THis is up from the Loowit trail as well.
I love this place and most of the time in between the times I have been there are spent wondering when I will next be able to enjoy it's splendor.
Tview from the blast zone.