Underground river 'Rio Hamza' discovered 4km beneath the Amazon

[...]
Brazilian scientists have found a new river in the Amazon basin – around 4km underneath the Amazon river. The Rio Hamza, named after the head of the team of researchers who found the groundwater flow, appears to be as long as the Amazon river but up to hundreds of times wider.
[...]
guardian.co.uk

Krasse Sache - und es zeigt mal wieder, wie wenig wir tatsächlich über die Erde wissen.