- This article is about the Earth region. You may be looking for the runabout Tunguska.
Tunguska was an area on Earth's surface, in the Siberia region of the Asian continent. As referred to by Hikaru Sulu, in this area an unknown phenomena had taken place. In this, a unknown object had exploded over this area with the force of a ten to twenty megaton H-bomb. An unmanned Vulcan robot probe in the Sol system had diverted a cometary fragment heading for a highly populated area of central Europe, directing it instead toward sparsely populated region of Siberia, near Tunguska. (TOS novel: Prime Directive)