In 2005, I outlined what I considered to be some of the chances and challenges in the conservation of groundwaters and their dependent ecosystems (Boulton, 2005). My goal was to highlight the conservation significance of the hydrological linkages of surface waters and associated systems (e.g. riparian zones) to groundwaters and how we might protect such 'open' aquatic ecosystems. I briefly reviewed what we knew then about the ecology of groundwaters and ground-water dependent ecosystems (GDEs), explored some of the threats disrupting flows of water and energy to these systems, and concluded by identifying chances and challenges in their conservation. I said then — and I still believe — that our biggest challenge as aquatic conservationists is to increase (and sustain) public and political awareness of the importance of groundwaters and GDEs, how they are threatened, and the need for applied research on groundwater processes and response functions to help managers assess groundwater resource use. My pleas echoed those of others (e.g. Humphreys, 2000; Danielopol et al., 2003); now it is time to take stock of their effectiveness. What have we learned in the last half-decade? How successfully are we using this information to protect and conserve global groundwaters and their dependent ecosystems?