In this paper a short introducO on is given to the Danish hydrological observatory—HOBE. We describe characteristics of the catchment, which is subject to experimental and modeling investigations. An overview is given of the research reported in this special section of the journal, which includes 11 papers of original research covering precipitation, evapotranspiration, emission of greenhouse gasses, unsaturated flow, groundwater–surface water interaction, and climate change impacts on hydrology.