This paper presents a collaborative ocean resource interoperability initiative using the Ferrybox project as a context. The goal is to facilitate resource and data interoperability in oceanographic Earth Observation (EO) to allow multi-use of ocean data. The study investigates various technologies and methods, particularly the semantic web approach. By following a semantic web-based knowledge life cycle, activities on ontology modeling, semantic web annotation of domain resources, and their storage as RDF triples and publishing/reuse are carried out. A semantic web infrastructure is set up to accommodate these activities. Based on domain knowledge acquired, an ontology-based domain reference model is developed to provide domain conceptualization and assumptions in the Ferrybox project. Through the use of different semantic web tools and interfaces, operational resources such as sensors and platforms, as well as observation datasets in the Ferrybox project, are semantically annotated on the ontology-based domain reference model. The ontology and semantic annotations are stored as OWL and RDF triples in a semantic web triple store where they can be further reused to facilitate dynamic ontology-driven semantic annotation, linked data browsing, query, and data integration. The study demonstrates the potential of semantic web technology to improve data interoperability in oceanographic EO. By using semantic annotations, the system enables better interoperability within the Collaborative Ocean initiative, facilitating the multi-use of ocean data and making more EO data available on the semantic web. The paper also discusses the technical implementation of the system, including the use of Java and PHP as main development languages, and the deployment of the system on multiple nodes of different operating systems to demonstrate a distributed Service Oriented Architecture (SOA). The system components/services are deployed to demonstrate a distributed SOA, with the semantic web infrastructure supporting semantic annotation, browsing, query, and inference. The system also includes a semantic web layer that provides semantic web-based functionalities such as domain resource annotation, browsing, query, and inference. The web layer allows applications to interface end users with the functionalities offered by the semantic web layer in the context of the domain. The system also includes a COG web client that allows manual and semi-automated semantic management of oceanographic resource sharing and collaboration using semantic web functionalities offered in the semantic web layer of the system. The system also supports more intelligent, semantic web-driven operations, such as data post-processing and smart sensor activities in the future. The study also discusses the mashing up with OGC services, demonstrating interoperability potential between RDF triples and OGC standards. The paper concludes that the semantic web approach can improve data interoperability in EO by adding a semantic web layer where the ontology-based domain reference model is used to enrich EO resources with standard metadata shared within the community.This paper presents a collaborative ocean resource interoperability initiative using the Ferrybox project as a context. The goal is to facilitate resource and data interoperability in oceanographic Earth Observation (EO) to allow multi-use of ocean data. The study investigates various technologies and methods, particularly the semantic web approach. By following a semantic web-based knowledge life cycle, activities on ontology modeling, semantic web annotation of domain resources, and their storage as RDF triples and publishing/reuse are carried out. A semantic web infrastructure is set up to accommodate these activities. Based on domain knowledge acquired, an ontology-based domain reference model is developed to provide domain conceptualization and assumptions in the Ferrybox project. Through the use of different semantic web tools and interfaces, operational resources such as sensors and platforms, as well as observation datasets in the Ferrybox project, are semantically annotated on the ontology-based domain reference model. The ontology and semantic annotations are stored as OWL and RDF triples in a semantic web triple store where they can be further reused to facilitate dynamic ontology-driven semantic annotation, linked data browsing, query, and data integration. The study demonstrates the potential of semantic web technology to improve data interoperability in oceanographic EO. By using semantic annotations, the system enables better interoperability within the Collaborative Ocean initiative, facilitating the multi-use of ocean data and making more EO data available on the semantic web. The paper also discusses the technical implementation of the system, including the use of Java and PHP as main development languages, and the deployment of the system on multiple nodes of different operating systems to demonstrate a distributed Service Oriented Architecture (SOA). The system components/services are deployed to demonstrate a distributed SOA, with the semantic web infrastructure supporting semantic annotation, browsing, query, and inference. The system also includes a semantic web layer that provides semantic web-based functionalities such as domain resource annotation, browsing, query, and inference. The web layer allows applications to interface end users with the functionalities offered by the semantic web layer in the context of the domain. The system also includes a COG web client that allows manual and semi-automated semantic management of oceanographic resource sharing and collaboration using semantic web functionalities offered in the semantic web layer of the system. The system also supports more intelligent, semantic web-driven operations, such as data post-processing and smart sensor activities in the future. The study also discusses the mashing up with OGC services, demonstrating interoperability potential between RDF triples and OGC standards. The paper concludes that the semantic web approach can improve data interoperability in EO by adding a semantic web layer where the ontology-based domain reference model is used to enrich EO resources with standard metadata shared within the community.