The activity of attempting to reach the summits of a collection of peaks, usually those above some height or prominence in a particular region, or having a particular feature.
2009, Oliver Berry, The Lake District, →ISBN, page 104:
Everyone knows the English have an obsessive habit for collecting things, but there are few more obsessive pastimes than the sport of peak bagging.
2013, Michael J. Thompson, Margarida S. Cunha, & Mário J.P.F.G. Monteiro, Asteroseismology Across the HR Diagram, →ISBN, page 109:
When the identification is achieved, peak bagging can be performed; the theory of which is explained here. The practice of mode identification and peak bagging is developed through the use of hare-and-hound exercise.