MIT WHOI Joint Program graduate student Meagan Gonneea is a chemical oceanographer interested in groundwater. Groundwater that enters the coastal ocean from underground aquifers carries nutrients and pollutants, but scientists have lacked good techniques to measure that flow. Gonneea travels to the Yucatan Peninsula, where she is developing a method to use coral skeletons to track the flow of groundwater into the coastal ocean. In this video she describes her work and reveals some of the secrets of this "hidden river".