Mother Mountain is a series of peaks in Mt. Rainier National Park that stretches from Mowich Lake to the Carbon River.   Third Mother Mountain is the peak located at the far NE end of the ridge.    The climb is typically done via the abandoned Carbon River Road, although strong parties have done the peak from Mowich Lake via Second Mother Mountain. Much of the route is off trail requiring good route finding skills. The final rock section to the summit is considered a moderate scramble. 

Other Information
Driving Distance from Portland 190 miles
Driving Time from Portland 4 hours
Relevant Books 100 Peaks at Mt. Rainier Cascade Alpine Guide vol.1, by Fred Beckey
Relevant Maps USGS: Mowich Lake
Useful Links