Thrihnukagigur crater is the only place on Earth where the anatomy of a volcano can be studied from the inside. When geologists journeyed into its heart, they discovered that a network of fissures links together distant volcanoes.

Additional funding for this program is provided by Millicent Bell, through the Millicent and Eugene Bell Foundation.

Funding for NOVA is provided by David H. Koch, the Howard Hughes Medical Institute, the Corporation for Public Broadcasting, and PBS viewers.