This Month in Photo of the Day: National Geographic Magazine Features

An expedition member walks on the cooled lava floor, turned red by the reflected glow of a lake, of a caldera in Nyiragongo volcano in the Democratic Republic of the Congo. "Down here you feel the volcano," says photographer Carsten Peter. "It's a low-frequency rumbling that pulses through your body—like being inside a giant subwoofer."

See more photographs from the April 2011 feature story "The Volcano Next Door."