From Summit Post: Mount Whittier is the highest point in the Mount Margaret Backcountry - part of the Mount Saint Helens National Volcanic Monument - and is part of a ridge system located just north of Mt. St. Helens and Spirit Lake. The views of the St. Helens crater from atop the ridge are some of the best anywhere in the Monument. Mount Whittier likely does not receive too many visitors. The easiest trail approaches eastwards from Norway Pass - although most hikers likely visit the nearby and slightly lower Mount Margaret (5858') to the south. Visitors may also be deterred by the Forest Service warning: "The Whittier Trail #214, in particular, is very narrow and crosses steep cliffs; it is not suitable for hikers that are uncomfortable with heights." The old trail is largely unmaintained but has several sections of easy class 3 scrambling along a narrow ledge. It's fine if it's dry, but if not, you may want a handline for safety. Mt. Whittier could easily be combined with nearby Mount Margaret (5858') as a day outing. 

Other Information
Driving Distance from Portland 120 miles
Driving Time from Portland 2 hours
Expected Duration Car to car in one day