Ocean Air Bubble
Photo: Mark Tipple
An air bubble ascending from the ocean floor contorts and twists into a semicircle as a wave breaks in the background. Captured as part of the Underwater Project.
Hang En Cave, Vietnam
Photo: Carsten Peter
Going underground, expedition members enter Hang En, a cave tunneled out by the Rao Thuong River. Dwindling to a series of ponds during the dry months, the river can rise almost 300 feet (91 meters) during the flood season, covering the rocks where cavers stand.
Tundra Trek, Svalbard
Photo: June Jacobsen
Brilliant day for a hike on the Arctic tundra, surprisingly alive with flora, as well as reindeer and arctic fox. It seems the mountains make their own weather on Svalbard, or at least cloud formations - this one no exception.
Stratus Clouds, Greenland
Photo: Bryan and Cherry Alexander
Eight hundred miles south of the North Pole, stalactite-like stratus clouds - churned by 90-mile-an-hour winds - and the light of a bruised dawn paint an apocalyptic portrait over Inglefield Bay.
Owyhee River, Idaho
Photo: Michael Melford
120 miles protected in Oregon since 1984 and 67.2 more since 1988; 171.1 miles protected in Idaho since 2009
Ivanhoe Reservoir, Los Angeles
Photo: Gerd Ludwig
in 2007, high levels of bromate - a carcinogen formed when bromide and chlorine react with sunlight - were found in Los Angeles’s Ivanhoe Reservoir. Today three million black plastic balls help deflect UV rays.
African Flower Mantid, macro photo by Bob Jensen :)
Baby Malamutes (by Devilstar)
Aerial view of Château de Chenonceau, France (by Baloulumix)