© Sputnik / Servicio de prensa del gobernador del Distrito autónomo de Yamalia-Nenetsia
One of the strange holes dotting the Yamal Pennisula in Siberia
RT takes a look at the possible origins of the so-called 'black holes' - massive craters that are being formed across the Yamal Peninsula in northern Russia.
Giant round craters seemingly appear out of nowhere in the remote areas of Western Siberia, mesmerizing and, sometimes, scaring nomadic reindeer herders and scientists alike.
One such crater opened up just last year, while more than a dozen others took several decades to form, researchers say. Some remain vast cavities, going as deep as 30 meters (98.5 feet). Others become lakes.
An anthropologist who studies the culture of the local Nenets people says she had witnessed a spontaneous formation of one such lake in the tundra.
"There was no lake, but larch trees. One night, after loud bangs, it was like an upside-down saucer, with the trees on the bottom and the roots on the surface," she says, adding that several days later a lake was formed, which is now considered sacred by locals.
Watch the full documentary here:
Comment: Also in central Alaska about 100 miles west of Fairbanks: