Summary:

The hollow earth has long been a popular alternative theory of the shape of the earth. Typically this theory also posits large holes at the North and South Poles which would allow entry into the interior. In his 1906 book, The Phantom of the Poles, William Reed presents a collection of reports of polar explorers on strange and unexplained phenomena, such as warm winds, deposits of dust, rocks embedded in icebergs, large ice-free areas, fresh water areas in the open polar ocean, and bizarre auroras, all in support of his belief that the polar areas are the vestibule to the interior of the hollow earth.