The glaciated region is roughly 89% forested with Noble fir, western hemlock, cedar species, pacific silver fir, mountain hemlock and several other tree species. Crossed by the Pacific Crest Trail, Olallie is in the shadow of Mount Jefferson within the Mount Hood National Forest. The volcanic peaks of Mount Jefferson and Olallie Butte, both located on the border of the Warm Springs Indian Reservation, overlook the area from the south and north. There are some meadows and marshes—Olallie Meadow, at , is the largest—and home to a former ranger station. Olallie Lake Guard Station is listed on the National Register of Historic Places and is near the west end of Olallie Lake.