The fire tower is probably the best-known sight at Cook Forest; off or Rt. 36, there is a one-way loop that leads to the parking area. The walk to the tower is not very long, and the tower can be climbed, offering a great view of the surrounding wilderness. An even more stunning view can be found at Seneca Point, which is in the same vicinity; a short trail off of the path that leads to the fire tower will take you to a massive boulder from which the Clarion River can be viewed.
More good news; even better sights of the river are possible via the aptly named River Trail. From the fire tower itself, simply follow the signs and blazes The trail will basically take you all the way down to the river and run along its length for a decent amount of time. Eventually, the trail will split; the River Trail heads back up the hill to ultimately connect with the one-way road you’ll be leaving on; because the trail doesn’t lead back to the starting point, you’ll have to walk on the road for a while, but because it’s in the wilderness and the speed limit is so low, it’s far more enjoyable than you’d think. If you’re not quite ready to head back to your vehicle, you can continue to walk along the river, via the Baker Trail (a portion of which also cuts through Crooked Creek). In either case, I highly recommend walking the River Trail if you’re up for it (note that the descent and ascent, while not steep, are relatively lengthy, though nothing that a Pittsburgher used to walking hilly streets would find too difficult).
The Sawmill Craft Center is, in my humble opinion, rather kitschy; the Black Bear Trail, which can be accessed via the same parking lot, is decent, but hardly a match for the River Trail. A far superior trail (actually, network of trails) can be found by the park office (also the site of many rental cabins). These trails are numbered and named, but beware; there are numerous intersections at which the map and posted signs do not coincide. I hope this doesn’t scare you off, because these trails really are worth checking out. I suggest starting with trail #7, which begins with a set of stone stairs; the trailhead is between the children’s fishing pond and the first of the cabins. Trail #7 is pretty much all uphill for its first half, but from there it’s basically flat, and for the most part, the rest of the trails are also flat, or else lead downhill (what else did you expect?!?).
From there on, it doesn’t really matter which trail(s) you decide to explore; they’re all pretty much the same, and all equally entertaining. The only other landmark you might wish to see is the swinging bridge, which connects trail #4 to trail #6; these two trails begin at the far end of the cabin area, and if you’re not up for a climb, it might be best to simply start with one of them, given that they’re relatively flat, easy walks.
Also in the area:
Depending on how much time you have, you might want to consider heading even further north, to the depths of the Allegheny National Forest. There is also another state park near Cook Forest, just outside of the boundaries of the Allegheny National Forest; called Clear Creek, it can be accessed off of Rt. 949.