According to geologists this hole in the ground, which from floor to ceiling is about 15 ft (5m) tall, was once filled with molten lava, presumably on it's way to blow out of some volcano or something. It is like an underground river, only it's about 1000 to 2000 degrees Fahrenheit (537 to 1093 C). Fortunately it's much cooler now. There are several places where the roof has caved in and so we can explore. This is at the Craters of the Moon National Monument in Idaho, U.S.A.
It is called Indian Tunnel because it is very close to some sites that the Shoshone Tribe was believed to have used for religious ceremonies.