While a short hike, the trail to the High Rock Lookout Tower is all about the views. You'll gain approximately 1,300 feet in just over a mile once you leave the trailhead, topping out on a dramatic ridge with vertiginous and expansive views in all directions. Despite the exposure at the end of the hike, the trail mostly sticks to the dense forest of hemlock and noble fir, so it is a pleasant climb along the way. In the summer, a diverse understory of wildflowers and huckleberries line the trail.
Begin on High Rock Lookout Trail 266, which leaves the parking area right off of NF-8440. You'll be able to see the tower from early on in the hike, which is good for motivation. Note that a spur trail leads off to the right, but this soon rejoins the main trail and is best skipped. The trail remains in good condition, and you'll find a few benches to help with recuperation after the switchbacks. You'll leave the forest after a little more than a mile and continue along the ridge. The magnitude of the this ridge's prominence begins to sink in at this point, and the impression only increases as you approach the tower.
Built in 1929, the tower is no longer in use, but it is often left open in the summer season. Very little sits between the tower and the sheer drop to Cora Lake below, so be very cautious as you explore this ridge. Views from the tower are magnificent: in addition to incredible views of Mount Rainier, you'll see Goat Rocks, Mount Adams, Mount St. Helens, and even Mount Hood.