DK Metcalf said in an interview with The Athletic that he believes another civilization exists inside Earth and linked that claim to Antarctica.
Antarctica travel restrictions are central to his argument: Metcalf said people can go to Alaska or the North Pole but cannot simply book a trip to Antarctica.
The Athletic noted Antarctica tourism does exist, mostly by ship between November and March, though there are no commercial airports and many non-commercial flights are government-controlled.
Metcalf also questioned supposed meetings of world leaders in Antarctica, while the outlet said it found no verifiable evidence of such gatherings.
Aaron Rodgers shares Metcalf's interest in conspiracy theories, but Metcalf said he held those views before the Steelers teammates bonded over them.