A day you will not soon forget, the Fin is an absolute gem and is world class for a feature at it's grade in the alpine. Here you have a blade of granite containing several distinct peaks jetting out of the beautiful alpine meadows above Harrison Lake and the Beehive Lakes. All in all, you will climb 5 peaks in a day, with the middle peak containing some vertigo inducing exposure. Don't underestimate this route, there is more 5th class climbing than you would think and the Fin is extremely exposed although with some route finding it goes around 5.4. This route includes 6 peaks including Harrison Peak, as long as you summit each peak, staying on the ridge proper is up to you. There are some times when using the ridge has it's advantages and others when you can skirt the ridge in a quicker way.
Run down the Upper Pack River Rd for about half a mile to an obvious clearing and head towards Beehive Dome, once you've gained the base of the dome there's a bunch of ways up. If you stay on the far left side you will keep it at a 3rd class grade. So now trudge up this beast. Once you're at the top enjoy the rad views, and continue on up the ridge. This will be a little bit bush-wacky, following this you will hit the next peak. There is a third class way and a fourth class way up. Pick your poison. Once there, you'll start scrambling down and trend to the right. Your next peak is fairly obvious and goes no harder than third class. Once you top out this peak it is game on and I do mean game on. The nice wide ridge that you passed before turns into an exhilaratingly thin ridge with sustained 4th class scrambling and at least the way I went, some mild 5th classy terrain. From here, delicately continue along the ridge until you hit the base of the Fin. The tricky part of the fin is definitely not the difficulty, 5.6-5.7 at most. You'll have hundreds and hundreds of feet of exposure on both sides of you. Epic. Once you top out the fin, your next objective is the obvious peak in front of you, mild 3rd class on the fifth peak. Once you have finished the 5th peak, traverse over towards Harrison Peak which is off-trail bushwacking and summit again with 3/4th class climbing to get to the peak. Once finished, head down the same way you went up and then make a left turn down to Harrison Lake (you'll have to pop over a little ridge). Once down at the lake take the Harrison Lake trail back to your rig and revel in the awesome day you just pulled off!
There is a great description of this route in the Climber's Guide to North idaho and the Cabinet Wilderness.
https://www.mountainproject.com/route/116697055/beehive-five