The world famous Marble Arch Caves provide a glimpse into a fascinating, natural underworld of rivers, winding passages and lofty chambers and are a key site within the wider UNESCO Global Geopark. Join GSNI, Arup and Geopark staff to hear about the hydrology of these fascinating caves while watching the Owenbrean River turn a luminous shade of green! Dye tracing is a method used by hydrologists to track and trace the flow of underground streams and rivers. Learn about the importance of dye tracing in the field of Geology and the various equipment used to carry out these exciting experiments. Find out more about the tracing experiments that have been carried out in the wonderfully wet counties of Fermanagh and Cavan.