Most of this trail is pretty mellow, but the climb out of the NW basin is a wet scramble and the Knife Edge is exposed and exciting. This is a long run, and you'll get up above treeline - it's not a trivial trip!
There's a big stream crossing at mile 6. Also, the trail up from Davis Pond in the NW basin is very steep, mossy and wet.
I have always wanted to do this loop at Baxter state park in Maine around, up and over Katahdin. We made a day trip out of it which made for a very long day but good times were had by all.
Start out at the Roaring Brook trailhead. From there, head up to Russell Pond on the Russell Pond Trail
. This is an easy section of trail that should flow along nicely. Only about a half mile in is a great view over a pond of the Mount Katahdin massif. About a third of the way along, there is a huge glacial erratic that the trail goes around. There's a stream crossing at mile 6, that could be sketchy at high water. Take a left at about 6.4 miles (10.3k) onto the Northwest Basin Trail
The first few miles of this trail are a gradual climb that is very doable. As you get to the ponds, it gets a bit more tricky but the views open up of the most remote basin in Baxter. The boulders get bigger as do the holes between them. Part of the trail follows a steep stream on bedrock for a bit. A quick side trip to Davis pond is worth it.
Once above treeline, continue to the saddle, up to the peak, across the Knife Edge to Pamola and then down the Helon Taylor Trail
. This trail is exposed at the top, bushy in the middle, and ledgy on the bottom. It ends at that Chimney Pond Trail
, 0.2 miles from the ranger station.