Named for a 19th century prospector and settler, Henline Mountain in the Opal Creek Wilderness is everything you'd expect it to be if you're familiar with the area. The tall, uncut old-growth woods, steep slopes with nearby sheer cliffs, rugged mountain views, occasional wildflower meadows and historically significant former lookout site make this a diverse adventure.
This is prominently a switchback trail. It begins by climbing steeply through dense forests of Douglas firs and western hemlock with salal and vine maple fully occupying the underbrush. Views are infrequent initially with a couple of rock outcroppings offering vistas unobstructed by the forest. On a clear day, Marys Peak in the coast range across the Willamette Valley can be seen to the west. As the trail seems to endlessly switchback higher and higher, bear grass begins to occupy the trail's periphery. Then the trail levels out as it rounds the western ridges of Henline Mountain and the first view of Mount Jefferson's top can be seen before opening to a scree field just below the lookout ridge.
Panoramic views of the whole Opal Creek Wilderness are a treat from the old lookout site. To the north, one can see the interestingly named Nasty Peak (also known as Not Nasty Peak) with Stack Creek Dome just below it. The road to Jawbone Flats as it disappears into the Bull of the Woods Wilderness is also visible to the west. But the highlight of this view is Mount Jefferson, high above all the forested peaks to the southeast. Little remains of the former lookout, save a few pieces of rebar. This site ends the designated trail; however, if you're feeling adventurous, you can proceed to the actual summit of Henline Moutain via the volunteer-maintained ridge trail.
Skirting the ridge has the benefit of additional views toward the Willamette Valley as the trail crosses a steep, vast, wildflower-filled meadow. The trail then ascends sharply and roughly through dense forest via several short switchbacks before leveling out on the Henline Mountain shoulder. There is a break in the trees that allows for a distant, somewhat obstructed view of Mount Hood to the north and again, Mount Jefferson to the southeast. The trail proceeds on several more yards before ending in thick forest at the true summit.