Scientists have found a gigantic underground river flowing thousands of feet below the world's second longest river Amazon.

Researchers at the department of geophysics of the Brazil National Observatory have showed evidence of the existence of an underground river that flows 13,000 feet beneath the Amazon.

The body of the water has been named after Valiya Hamza, who led the research and found that the Amazon rainforest has two separate drainage systems: the surface drainage through the Amazon and the flow of groundwater through the deep sedimentary layers, the Hamza.

The width of the Hamza is said to be 6,000 kilometers long, flowing 13,000 feet below the Amazon. Both rivers flow from west to east. The Amazon ranges from 1 kilometer to 100 kilometers in width, while Hamza ranges from 200 kilometers to 400 kilometers, however the Hamza flows at only a fraction of the speed of Amazon.

The starting point of the underground river is believed to be the Acre region under the Andes, and it reaches the sea at Foz do Amazons, flowing through basins of rivers Solimões, Amazon and Marajo.

It is likely that this river is responsible for the low level of salinity in the waters around the mouth of the Amazon, said a statement released by the National Observatory.

The latest findings are based on data analysis temperatures of 241 wells drilled by Petrobas in the 1970s and 1980s in the Amazon region. The results obtained allowed the identification of movement of groundwater in depths of 4,000 meters in this region.

Computer simulations show that the groundwater flow is predominantly vertical to about 2,000 feet deep, but changes direction and becomes horizontal at greater depths.

According to the researchers, the presence of the Rio Hamza River might account for the relatively low salinity of the waters around the mouth of the Amazon.

Hamza said that the studies are still at an early stage. He hopes that he'll be able to confirm the subterranean flow of water by the end of 2014.

Amazon is the second longest river in the world and has the largest drainage basin in the world. The bulk of Amazon, which accounts for about one-fifth of the world's total river flow, flows through tropical rainforest. The river merges in to the Atlantic Ocean in a broad estuary about 150 miles wide.

If the estimated length of 6,000 kilometers is confirmed, Rio Hamza would follow the Mississippi as the fifth-longest river in the world.