Probably the most fantastic expedition ever conducted by sea to a place never seen from sea level.
The North Pole Inner Earth Expedition has gotten funding from a New York production company with a departure date set for July, 2013. According to legend, in an oceanic depression above the Arctic Circle is an entrance to an Inner Earth, and through the use of gyroscopes on the ship, they'll be to identify such a depression.
In ancient times, the idea of subterranean realms seemed arguable, and became intertwined with the concept of "places" such as the Greek Hades, the Nordic svartalfheim, the Christian Hell, and the Jewish Sheol (with details describing inner Earth in Kabalistic literature, such as the Zohar and Hesed L'Avraham - Hollow Earth Hypothesis).
The idea of a subterranean realm is also mentioned in the Vedic texts such as the Puranas, according to one story in the Puranas there is an ancient city called Shamballa which is located inside the earth, the belief in Shamballa as a city inside the earth is also found in Tibetan Buddhism. The concept of a subterranean land inside the earth is popular in mythology, folklore and legends in ancient times.