The 26th annual National Geographic Traveler Photo Contest is now accepting submissions. Official categories include: “Travel Portraits”, “Outdoor Scenes”, “Sense of Place” and “Spontaneous Moments”. The contest is accepting entries until June 30. Photo: “Forest lights”. Aurora Borealis over the forest of the Pyhae Luosto National Park, Finland. (Photo and caption by Nicholas Roemmelt/National Geographic Traveler Photo Contest)

A Naga sadhu, or naked Hindu holy man, performs a ritual inside his tent during Kumbh Mela, or Pitcher festival, at Trimbakeshwar, India, Friday, August 28, 2015. Hindus believe taking a dip in the waters of a holy river during the festival will cleanse them of their sins. The festival is held four times every 12 years. (Photo by Rajanish Kakade/AP Photo)

A member of the German wireless police picks up signals on the radio equipment he carries on his back, while his colleague takes notes. (Photo by General Photographic Agency/Getty Images). Circa 1925

Mulan Jamilah, a 6-year-old Bengal tiger, kisses caretaker Abdullah Sholeh, 33, in the garden beside their home on January 20, 2014 in Malang, Indonesia.

Revelers throw colored corn starch into the air as they celebrate the 2015 Holi (Festival of Colors) at the Krishna Temple in Spanish Fork, Utah on Saturday, March 28, 2015. (Photo by Rick Bowmer/AP Photo)

David Guttenfelder was born in Iowa and graduated from the University of Iowa with a Bachelor of Arts in cultural anthropology. He has worked for the AP since 1994 based in Kenya, the Ivory Coast, India and Japan. He is currently AP’s chief Asia photographer and his feature work has been used prominently in editorial publications throughout the world including Time and National Geographic. Photo: U.S. soldiers from the 2nd Battalion, 12th Infantry Regiment, 4th Brigade Combat Team, fire mortars at known enemy firing positions from a base in the Pech River Valley in Afghanistan's Kunar province, Saturday, October 24, 2009. (Photo by David Guttenfelder/AP Photo)

A Uyghur boy sits atop a horse as he has his picture taken outside the Id Kah Mosque before the Eid holiday on July 28, 2014 in old Kashgar, Xinjiang Province, China. Nearly 100 people have been killed in unrest in the restive Xinjiang Province in the last week in what authorities say is terrorism but advocacy groups claim is a result of a government crackdown to silence opposition to its policies. China's Muslim Uyghur ethnic group faces cultural and religious restrictions by the Chinese government. Beijing says it is investing heavily in the Xinjiang region but Uyghurs are increasingly dissatisfied with the influx of Han Chinese and uneven economic development. (Photo by Kevin Frayer/Getty Images)

Young girls attend a training session in MGFSO Olympic reserve school in Moscow on May 30, 2016. (Photo by Kirill Kudryavtsev/AFP Photo)