Expeditions to the Hollow Earth

From About.com:
• In the early 1800s, an American army captain named John Cleves Symmes was an enthusiastic supporter of the idea of a hollow Earth. He believed the theory proposed by Sir Edmund Halley, the famed astronomer, that there were five concentric spheres within the planet, each capable of supporting life and illuminated by a glowing atmosphere (which was responsible for the aurora borealis seen in the northern latitudes). Symmes was such a champion of this idea that the holes at the poles actually became popularly known as Symmes' Holes. He traversed the U.S. trying to raise money for an expedition and even petitioned Congress for financing. Nothing ever came of it.

• In 1824, a wealthy doctor is said to have mounted an expedition to find Symmes' Hole at the south pole, but the journey was unsuccessful.

• In 1893, Dr. Fridtjof Nansen designed his own ship, the Fram, to explore the north pole. Hollow earth followers have cited his reports of warm winds coming from the north, of red and green pollen covering the snow in some areas, and of fresh driftwood found in the Arctic Ocean ice, where there are no trees. All of these anomalies, hollow Earthers say, have come out of the warm northern opening.

• In 1926, Admiral Richard E. Byrd became the first person to fly over the North Pole. In 1929, he successfully flew over the South Pole. Although officially, of course, Byrd discovered no entrances into the Earth's interior at either pole (he certainly wasn't looking for any), staunch hollow Earthers contend that he really did find a hole at the North Pole. They say he may have even flown as far as 4,000 miles into the interior, although there's no evidence to support this.

• In 1939, the Americans and Germans were in a race to explore and claim lands in Antarctica. President Roosevelt sent Admiral Byrd to the frozen continent to thwart any German claims to Antarctic lands in the Western Hemisphere. Hollow Earthers have proclaimed that this was actually a secret mission to beat the Nazis in the exploration of "the land beyond the poles."

• In 1947, Admiral Byrd is said to have made a secret flight to the North Pole to find this land beyond the pole.The "evidence" for this flight comes from a highly controversial "lost diary" kept by Byrd and miraculously found in the 1970s by "The Society for a Complete Earth." In it he writes that as he looked down from his plane, he saw not snow, but green vegetation, grassy valleys and mountains not shown on any map. Very few take this diary - or the flight itself - seriously.