Huge Hidden River Found Under Amazon

Thought the Amazon river was impressive, covering more than 4 million square miles in South America? Try the hidden river beneath it, which apparently equals the Amazon in length and is up to hundreds of times wider. Dubbed the Rio Hamza (after the head of the Brazilian team that found it) the secret waterway also flows west to east but is 125 miles to 250 miles wide, unlike the Amazon's width of about 1 to 60 miles.

Researchers stumbled on the Rio Hamza by analyzing data from 241 abandoned wells dug in the area by the petrochemical company Petrobras in the 1970s and 1980s. Temperature changes in the wells told them there must be an underground river, the Guardian reports. The researchers, who presented their findings in Rio de Janeiro last week, also said the Hamza's groundwater flowed almost vertically for around 2,100 yards, then ran almost horizontally until pouring out into the Atlantic Ocean. (More Amazon river stories.)