Mark Thiessen has been a photographer with National Geographic since 1990 and on staff since 1997.
Mark is widely published in all areas of the National Geographic Society, including National Geographic magazine, National Geographic Adventure magazine, and National Geographic Traveler magazine. National Geographic books that feature Thiessen's work include Return to Midway, which documents the discovery of the U.S.S. Yorktown, and Baseball as America, a look at the Baseball Hall of Fame.
Thiessen has contributed to many articles for National Geographic magazine, including "Monsters of Madagascar" (August 2000), "Russian Smokejumpers (August 2002), "Search for Other Earths" (December 2002), and "Nanotechnology" (June 2006).
In 1996, Thiessen began a personal photography project on wildland firefighters that took him to the front lines of wildfires every summer. To better understand the world of this little known subculture, he became a certified wildland firefighter. An award-winning online piece, “FireCall”, features Thiessen's photographs and interviews with a veteran wildland firefighter. Thiessen was also profiled for an episode of the National Geographic Channel's Out There series.