A hydrogeologist studies the ways that groundwater (hydro) exists within and moves through the soil and rock of the earth (geology). How we use this knowledge for the good of the environment and society will lead to our success as hydrogeologists and environmental game-changers. Within the broad field of hydrogeology there exist several specialist domains. One may be more of a specialist in groundwater supply, resource management and monitoring issues. Or one may concentrate on subsurface contamination issues.