Most readers of National Geographic probably don't realize that the photographers who produce those stunning images aren't on the magazine's staff; they are freelancers who work under contract for individual stories.
The Photo Society website features images, blogs and vignettes of what it takes to do this job.
Photographer Randy Olson addresses the question of how to become a Geographic photographer:
“It is not easy or glamorous. And this is not where you begin your career. You are competing with world-class documentary photographers and within that genre there are men and women who are the absolute best at their specialty.