Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)

Waves crash over lava as it flows into the ocean near Volcanoes National Park in Kalapana, Hawaii on November 27, 2012. A volcano on Hawaii's largest island is spilling lava into the ocean, creating a rare and spectacular fusion of steam and waves that officials said on Tuesday could attract thrill seeking visitors if it continues. (Photo by Hugh Gentry/Reuters)

Long streams of red-hot lava flow down the southeast crater of Mount Etna, Europe's tallest and most active volcano, seen from Zafferana Etnea, Italy, June 11, 2022. (Photo by Antonio Parrinello/Reuters)

Shortlist, open competition, lifestyle. Healing Vibes – the hot springs of Bagno Vignoni in Italy flow out at a temperature of about 49°C. They were appreciated by the Romans for their healing powers, and have been used as therapeutic treatments since the 12th century, under Emperor Federico II. (Photo by Stefano Butturini/Sony World Photography Awards)

An aerial view of people visiting the roaring Hukou Waterfall on the Yellow River on August 11, 2025 in Yan'an, Shaanxi Province of China. Hukou waterfall is witnessing an increasing water flow lately. (Photo by Liu Yijiang/VCG via Getty Images)

The “Sarandi” stream, dyed red due to unknown contaminants allege residents, flows into the Río de la Plata on the outskirts of Buenos Aires, Argentina, February 6, 2025. (Photo by Rodrigo Abd/AP Photo)

Pamukkale, Turkey, is home to these terrace pools, formed by the build-up of carbonate mineral from the warm water flowing from the thermal springs above. (Photo by Image Courtesy of Jennifer Hayes/Getty Images)

Lava flows from an eruption of a volcano on the Reykjanes Peninsula in Iceland on March 28, 2021. A week on, big crowds of Sunday hikers flocked to the Fagradalsfjall area to see up close Iceland's latest volcano eruption, as the gentle lava flow allowed people to get close to he eruption some 40 km west of Iceland's capital Reykjavik. (Photo by Halldor Kolbeins/AFP Photo)