Continuous observation of the marine environment has been an attempt on a global scale over the last two decades, as the role of the oceans in climate formation has become apparent and the need to systematically record a set of parameters for assessing the impact of climate change has been highlighted. In this context, the World Organisation GOOS (Global Ocean Observing Systems) has been created, under the auspices of UNESCO, with the aim of coordinating and interconnecting individual observation systems, so that overall information on the state of the oceans is available on a systematic basis. On the other hand, the protection and management of surface water bodies requires a wealth of data coming from reliable measuring systems. In Greece, both the quantity and quality of these data are insufficient, with the relevant infrastructure being fragmented into various bodies and services. Within the framework of the project, it is planned to create a national network of hydro-environmental information, which will be freely available and meet the needs of the technical and scientific community of the country and the public, in data, as well as the requirements of the relevant European Directives (2000/60/EC, 2007/60/EC). The research infrastructure ‘Greek Integrated Monitoring System, Forecasting and Technology of the Seas and Surface Waters’ offers an overall monitoring of both marine environments and surface water, constituting the Greek contribution to the respective global efforts. It is a modular research infrastructure, with key coordinators in its two main thematic axes, the Institute of Oceanography of the Hellenic Centre for Marine Research (HELKETHE) for the observation and forecasting of the seas, and the School of Civil Engineering of the National Technical University of Athens (NTUA) for surface waters. In particular, the systematic monitoring of the marine environment is implemented using a series of logging platforms that have the ability to send their data in real time: Fixed position floating stations recording a range of marine environment parameters as well as atmospheric information; (b) Argo profiling floats; (c) autonomous underwater watercraft (gliders), d) FerryBoxes systems, mounted on passenger ships; In addition, a system of numerical models produces on a daily basis short-term forecasts of atmospheric, wave and hydrodynamic conditions of the marine environment and the state of the ecosystem. Regarding the “Open Water Information Network”, it aims to develop an integrated information system for the collection, management and free diffusion of hydrological, geographical and environmental information concerning the country’s surface water resources. The system will receive and process metering data from automated telemetric stations, and will cooperate with research and state databases that have historical data and/or manage real-time data. The infrastructure data will be freely available to interested parties, while access to individual parts of the infrastructure will be possible for the research and scientific community of the country to carry out actions jointly with the bodies that make up the infrastructure.