As the popularity of The Mountaineers expanded, local groups organized activities to supplement those carried on by the Seattle members. The Everett branch began a Local Walk program in 1910, and the Tacoma Branch organized their Local Walk program in 1912. Outings, spanning a two or three-week period, were organized to celebrate the distinct natural wonders of the Pacific Northwest. The first major outing chosen was a 1907 exploration of the Olympic Mountains. A climb of the eastern side of Mount Baker was the key element of the 1908 Outing. The Mountaineers chose Mount Rainier as the location for their third "Summer Outing," held in 1909. A few of the members climbed to the summit of "The Mountain."

In 1911 planning started on a second Mount Rainier Outing. The March 1912 Mountaineer Bulletin included an outline of the proposed route. Also published was notice of a "Conference between Seattle And Tacoma Clubs Looking To Unity Of Purpose And Better Organization for The Development Of Rainier National Park." At the meeting, sponsored by the Commerce Clubs and Rotary Clubs from both cities, Asahel Curtis led a discussion of how The Mountaineers could support a bill before Congress for "creation of a National Park Bureau," resulting in the 1916 birth of the National Park Service. They also discussed the need for improving the park trail system and widening and extending park roads.