World’s Greatest Mountains 2012 Calendar. This fantastic World’s Greatest Mountains 2012 Calendar features the world’s major mountains and mountainous regions. Mountain ranges account for 24% of the world’s total land mass and are some of the most uninhabitable places on earth due to their sheer height, terrain and climate although many are used for logging, mining, grazing, or recreation including hiking, backpacking, mountaineering, rock climbing, skiing, and snowboarding. Enjoy the spectacular sights of our mountain ranges in this stunning World’s Greatest Mountains 2012 Calendar!