Maurice Krafft's bootlaces are melting. Maybe I shouldn't be surprised. I'm standing with Maurice—a pioneer in the perilous business of filming volcanoes—on the crater floor of an erupting volcano in Tanzania.

The Maasai's sacred mountain, Ol Doinyo Lengai, is stirring. The crater floor bubbles with hot lava interspersed with cooling black and white lava. Maurice suggests walking on the safer, cooler, white areas, but visions of melting bootlaces keep flashing in my mind. "It is not a worry," he says with his French inflection. "My boots just fell through into the hot red lava. Walk lightly." He offers to go first. It's a test of faith—but no one has better credentials to navigate the floor of an erupting volcano. Maurice and his wife, Katia, were often the first to arrive when volcanoes erupted around the world; over two decades they filmed more than 150 of them. We cross an infernal landscape punctuated with spewing lava. In a few hours, my bootlaces are melting too, but, like Maurice, I don't care. We camp on a dirt ridge for three days. The nights are breathtaking. The lava glows fiery red. The stars sparkle in the clear African sky. I know now why this 9,700-foot (2,956 meter) volcano is sacred to the Maasai. "Volcanoes are bigger than us," Maurice always said. "We are nothing compared to them."

In 1991 Maurice and Katia Krafft died while filming at Japan's Unzen volcano. A pyroclastic flow unexpectedly swept onto the ridge where they stood. "I am never afraid because I have seen so much eruptions in 23 years that even if I die tomorrow, I don't care," Maurice once said.

Indonesia—a place the Kraffts visited many times—is a volcano hot spot. It is also a place where volcanoes are a religion. This month writer Andrew Marshall and photographer John Stanmeyer discover how volcanoes have shaped that country's life and culture. "Volcanoes are the thrones of the gods," a Balinese tycoon told Marshall. The Kraffts showed us the view from those thrones.

Photograph by Maurice and Katia Krafft, Conservatoire Régional de l'Image