One of the most remote areas in the world seems to be slowly turning into something resembling a slice of Swiss cheese. Two new huge holes have been discovered in a Siberian region nicknamed "the end of the world," reports the Siberian Times. A 260-foot-wide crater found in the area caught the world's attention earlier this month, and now researchers and reindeer herders have uncovered two more: one with a diameter of around 50 feet, and another—which nearly swallowed the herders who stumbled across it—with a diameter of only about 13 feet but an estimated depth of up to 328 feet, Gizmodo reports.
At the larger of the two, "there is also ground outside, as if it was thrown as a result of an underground explosion," says a regional lawmaker who inspected the site from a helicopter. "It is not like this is the work of men, but [it] also doesn't look like natural formation," says one of the Russian experts puzzling over the phenomenon. Some of the wilder theories about the formation of the holes include aliens and weapons testing, but the leading theory suggests that they're caused by natural gas deposits bursting, NBC reports, possibly the result of warmer temperatures. (Another Siberian crater, this one 62 miles wide, is believed to sit on top of a diamond field holding "trillions of carats.")