What's the tallest volcano in the world?

The highest volcano is Ojos del Salado in Chile. It is 22,589 feet (6,887 m) tall.

Steve Mattox

Photograph by J.D. Griggs, U.S. Geological Survey, January 10, 1985.

From base to summit, the tallest would be Mauna Kea, which, when measured from its base on the ocean floor, is more than 30,000 feet high.

Scott Rowland