Cave diving (IMAGE) Northwestern University Caption The eastern Yucatán Peninsula study region is pierced by vast interconnected flooded tunnels, that function as underground rivers. The groundwater is the only source of potable water for the whole region. Credit Natalie Gibb/Under the Jungle Usage Restrictions add credit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.