The Hellenic Integrated Marine Inland Water Observing, Forecasting and Offshore Technology System is a large-scale, distributed national Research Infrastructure that includes two distinct components for the management of water resources in Greece; the marine and the surface waters. The integrated research infrastructure of HIMIOFoTS supports the continuous monitoring of the water environment together with the production of forecasting products for the marine environment through well-established hydrodynamic, waves and ecosystem numerical models using state of the art techniques for the assimilation of data collected from satellite and in situ observations. Open access is provided to the data from the marine and surface water monitoring networks as well as to the related forecasting products. In addition, operating at the core of Blue Economy, the HIMIOFoTS infrastructure promotes the development of value-added products and integrated services for the scientific community and society based on the needs of multidisciplinary stakeholders.