Talk-show host Oprah Winfrey interviewing cyclist Lance Armstrong during taping for the show "Oprah and Lance Armstrong: The Worldwide Exclusive" in Austin, Texas. The two-part episode of "Oprah's Next Chapter" will air nationally Thursday and Friday, Jan. 17-18, 2013. (AP Photo/Courtesy of Harpo Studios, Inc., George Burns)

On the western side of Mount Hood lies the longest glacier cave system in the contiguous United States. In 2012, these caves were mapped to a combined length of 7,166.8 feet by cave explorers Brent McGregor and Eddy Cartaya. Currently, the total passage length is hundreds of feet less. Glaciers are frozen rivers; they are always moving and changing... (Photo and caption by Josh Hydeman)

From towering elephants to tiny insects, photographers will be offering a rare insight into the natural world at this year’s Wildscreen Photography Festival 2014. The festival, formerly known as WildPhotos, is the UK’s largest wildlife photography show. The Wildscreen Photography Festival 2014 will be taking place between 24-26 October at London’s Royal Geographical Society. (Photo by Sam Hobson/Wildscreen Photography Festival 2014)

In this February 2, 2014 photo, people take pictures inside a cave at Apostle Islands National Lakeshore in northern Wisconsin, which has been transformed into a dazzling display of ice sculptures by the arctic siege gripping the Upper Midwest. (Photo by Brian Peterson/AP Photo/Minneapolis Star Tribune)

Fog hangs between pine trees in a forest near Neubrueck, eastern Germany, on November 20, 2012. Meteorologists forecast cloudy sky and temperatures around 5 degrees Celsius for the region. (Photo by Patrick Pleul/AFP Photo)

A cave diver in Anhumas Abyss, Bonito, Brazil. (Photo by Marcio Cabral/Epson International Pano Awards 2018)

“Danger in the mud” – a crocodile at Mana Pools National Park, Zimbabwe. The grand prize winner. (Photo by Jens Cullmann/World Nature Photography Awards 2022)

Demonstrators wear skull masks during an anti government protest, as Chile's President Michelle Bachelet delivers a speech inside the National Congress, in Valparaiso city, Chile May 21, 2016. (Photo by Ivan Alvarado/Reuters)