An active lava tube, Hawai'i Volcanoes National Park, Hawaii (© Tom Schwabel/Tandem Stills + Motion)(Bing United States)

The Hickman Bridge at Capitol Reef National Park, Utah (© Tim Fitzharris/Minden Pictures)(Bing United States)

Red-necked grebes in Germany (© Edo van Uchelen/Minden Pictures)(Bing United States)

Farmers collecting water lilies in the Satla marshland near Bagdha, Barisal, Bangladesh (© Mustasinur Rahman Alvi/Future Publishing via Getty Images)(Bing United States)

Edinburgh city skyline at night, Scotland (© Suranga Weeratuna/Alamy)(Bing United States)

Salt flats in San Francisco Bay (© Jeffrey Lewis/Tandem Stills + Motion)(Bing United States)

Spring Point Ledge Light in South Portland, Maine (© Haizhan Zheng/Getty Images)(Bing United States)

Aerial view of the island Pantaleu near Sant Elm, Mallorca, Spain (© Dimitri Weber/Amazing Aerial Agency)(Bing United States)

Cueva de las Manos (Cave of the Hands) in Santa Cruz, Argentina (© Adwo/Alamy)(Bing United States)

Joshua trees in Joshua Tree National Park, California (© Tim Fitzharris/Minden Pictures)(Bing United States)

Mount Tsubakuro near Azumino, Nagano, Japan (© Joshua Hawley/Getty Images)(Bing United States)

Herd of African elephants in Amboseli National Park, Kenya (© Susan Portnoy/Shutterstock)(Bing United States)

Boundary Waters Canoe Area Wilderness, Superior National Forest, Minnesota (© Dukas/Universal Images Group via Getty Images)(Bing United States)

Panther chameleon in Amber Mountain National Park, Madagascar (© Christian Ziegler/Minden Pictures)(Bing United States)

Chittorgarh Fort, India (© Anand Purohit/Getty Images)(Bing United States)

The Great White Roller Coaster at Wildwood, New Jersey (© John Van Decker/Alamy)(Bing United States)

Freshwater plants and tetra fish, Aquário Natural, Rio Baía Bonita, Mato Grosso do Sul, Brazil (© Michel Roggo/Minden Pictures)(Bing United States)

Källö-Knippla, an island in the archipelago of Gothenburg, Sweden (© Martin Wahlborg/Getty Images)(Bing United States)

Solar Impulse 2 flying over the pyramids in Giza, Egypt (© Jean Revillard/Solar Impulse2 via Getty Images)(Bing United States)

Beehives in the Muniellos Nature Reserve, Asturias province, Spain (© ABB Photo/Shutterstock)(Bing United States)

Faro de Playa Lago, Costa da Morte, Muxia, Galicia, Spain (© Carlos Fernandez/Getty Images)(Bing United States)

A burrowing owl chick and adult in South Florida (© Carlos Carreno/Getty Images)(Bing United States)

Menton, France (© Flavio Foglietta/Getty Images)(Bing United States)

Wheat field in Ukraine (© Yuriy Kulik/Getty Images)(Bing United States)

North Cascades National Park, Washington (© Ethan Welty/Tandem Stills + Motion)(Bing United States)

Kiteboarders and windsurfers off the Pelješac Peninsula, Croatia (© helivideo/Getty Images)(Bing United States)

Boundary Trail in Mount St. Helens National Volcanic Monument, Washington (© Don Geyer/Alamy)(Bing United States)

Bearded reedlings at a wetland in Flevoland, Netherlands (© Gert-Jan IJzerman/Minden Pictures)(Bing United States)

Baltic Sea in Estonia (© fotoman-kharkov/Getty Images)(Bing United States)

Regional Park of Migliarino, San Rossore, Massaciuccoli, Italy (© Stefano Valeri/Alamy)(Bing United States)

Blue linckia sea stars off New Ireland in Papua New Guinea (© Jurgen Freund/Minden Pictures)(Bing United States)