The offshore industry is engaged in the exploration and production of renewable and non-renewable energy and resources at sea.The offshore market is huge and has a major impact on economy, society, and environment. The exploration and exploitation of oil and gas is increasing, and is getting more and more complex.Additionally, the offshore wind industry is facing increasing demands, and complex offshore installations are needed.At the same time, the need for more cost effective, safer, and environmentally aware systems is compelling, and gives additional demands to the offshore industries.Operation and predictive maintenance activities are areas where the optimization of costs is considered an absolute necessity. This project answers these challenges by providing an offshore Internet of Things solution for fully automated (i)multidimensional monitoring, inspection, and predictive maintenance, and (ii)in-situ analysis of environmental, social, and ecological impact of offshore industry operations. This project goes beyond today's IoT initiatives by addressing(i) an extra challenging operational environment for IoT sensing and communication technology, namely the Arctic, and(ii) a new generation of fully connected multidimensional IoT consisting of static and mobile wireless sensor networks deployed underwater, on water/ice surface, above water, flying in air, and carried by people/workers. The unique approach to be taken is based on cutting edge platforms and infrastructure for connected smart objects in harsh and heterogeneous environments.Technology innovation of SIRENS spans through areas such as open, dynamic, re-programmable IoT platforms and networks, wireless sensing and communication technologies, multi-modal sensing, anomaly detection and predictive maintenance, self-organizing and autonomous systems, and swarms of exploring underwater robots and air-borne drones (The ABSTRACT of the original SIRENS H2020 proposal was 2700 chars and cannot be fully included)