The club hosts a wide range of outdoor activities, primarily alpine mountain climbing and hikes.
Among these original members were Henry Landes (University of Washington geology dean and later acting president), Edmond S. Meany (the father of the University of Washington Forestry school), the photographer Asahel Curtis, and Seattle photographer and North Cascades guide Lawrence Denny Lindsley.
The activities initially were local walks with the first trip being a hike through Fort Lawton to the West Point Lighthouse (now part of Discovery Park).
In 1915, a club outing became the first sizable group to hike around Mount Rainier and established the route that would later become known as the Wonderland Trail.
In 2008, the Mountaineers moved from Lower Queen Anne to an old naval building in Magnuson Park, now leased from the City of Seattle.
It was informally started in 1955 when a volunteer committee was formed to create a mountaineering training text from the materials that the club was using for its classes.