Cave Diver, Anhumas Abyss, Bonito, Brazil: The Anhumas Abyss is an underground cavern with a crystal-clear lake below, more than 260 feet (79 m) deep. A visitor must enter through a narrow opening at the top of the chamber and rappel into the cave. Snorkeling and scuba diving in the lake reveal amazing scenery. Distinctive, conical limestone stalagmites and stalactites occupy the lake and the surrounding area, some reaching 65 feet (20 m) high. (Photo by Marcio Cabral/Nature’s Best Photography Awards 2017)

A dog dives during a pet dog swimming contest at the Taoyuan Pet Center on July 31, 2005 in Chengdu of Sichuan Province, southwest China. Over 30 dogs have attended the match. According to state media, with the country's pet population growing fast, analysts predict that the market potential for the “pet economy” in China could reach a minimum of RMB 15 billion (about USD 1.85 billion). (Photo by China Photos/Getty Images)

A selection of winning images from the Life in Another Light photo contest 2020, from Kolari Vision. Here: Lights and Shadows in the Dolomites, in the landscape infrared category. (Photo by Tomasz Grzyb/Kolari Vision)

“Himalayan Dog”. This dog just appeared out of nowhere and followed us for an entire week during our trekking trip in the Himalayan outback. He always used to sleep in front of our tent and guarded us in the nights. When I decided to get up at 4 a.m. to climb the next 5000 m peak for sunrise he accompanied me as well. On the top he was sitting for the entire 30 minutes on this place looking straight into the countryside. Photo location: Ladakh, India. (Photo and caption by Sebastian Wahlhuetter/National Geographic Photo Contest)

“Lofoten Glow”. I was desperately searching a good sunrise spot this particular morning. Normally Storvatnet Lake is completely covered in snow, so you can only imagine my surprise when I saw these crazy ice formations almost being shot out of the frozen lake. I put my crampons on and took a big risk walking out. I could hear the ice cracking underneath my feet, and when you’re all alone in a fjord/canyon like this – the cracks are echoed and sound really frightening. Was it worth it? I sure think so! Photo location: Storvatnet, Lofoten Islands in Northern Norway. (Photo and caption by Stian Klo/National Geographic Photo Contest)

2014 Underwater Photography Photo Contest winners, Wide angle marine life category, 3rd place. (Photo by Valda Fraser/UnderwaterPhotography.com)

Winner of the National Park Foundation's photo contest; Honorable Mention: Fan Favorite. Grand Canyon National Park, Arizona. Three friends enjoy sunrise over the Grand Canyon. (Photo by Peter Blanchard)

“Are you here for the Winery Tour?” This is a Western Grey Kangaroo caught lounging in the wineries of the Adelaide Hills in South Australia. This past Autumn has been a spectacular time for wildlife viewing and I got lucky to spot this guy while mountain biking in the hills. Such a funny stance it just begs the question... Have you been drinking? ...and or... Are you here for the Winery Tour? Such a spontaneous moment I figured it would be perfect for an entry. I hope you like it! Cheers. Photo location: Adelaide Hills, South Australia, Australia. (Photo and caption by Greg Snell/National Geographic Photo Contest)