This paper discusses the development of a semantic web infrastructure for enhancing the interoperability of oceanographic Earth Observation (EO) data. The authors, from the National Oceanography Centre Southampton, present their work on the Collaborative Ocean Initiative, using the Ferrybox project as a case study. The Ferrybox project involves installing environmental sensors on commercial ships to collect near real-time data. The authors have created an ontology-based reference model to facilitate semantic annotation of relevant oceanographic resources, such as sensors and observations, in RDF format. This model supports common semantic management activities, including ontology management, semantic annotation, storage, and reuse. The infrastructure includes a layered structure with a domain layer for storing resources and metadata, a semantic web layer for enabling functionalities like annotation, browsing, and query, and a web layer for user interfaces. The system is implemented using Java and PHP, with tools like Protégé, TopBraid, and OntoWiki for ontology development and semantic annotation. The paper also explores the integration of geospatial metadata with OGC services, demonstrating the potential for interoperability between RDF triples and OGC standards. The authors conclude that adding a semantic web layer with an ontology-based domain reference model can significantly improve data interoperability in EO.This paper discusses the development of a semantic web infrastructure for enhancing the interoperability of oceanographic Earth Observation (EO) data. The authors, from the National Oceanography Centre Southampton, present their work on the Collaborative Ocean Initiative, using the Ferrybox project as a case study. The Ferrybox project involves installing environmental sensors on commercial ships to collect near real-time data. The authors have created an ontology-based reference model to facilitate semantic annotation of relevant oceanographic resources, such as sensors and observations, in RDF format. This model supports common semantic management activities, including ontology management, semantic annotation, storage, and reuse. The infrastructure includes a layered structure with a domain layer for storing resources and metadata, a semantic web layer for enabling functionalities like annotation, browsing, and query, and a web layer for user interfaces. The system is implemented using Java and PHP, with tools like Protégé, TopBraid, and OntoWiki for ontology development and semantic annotation. The paper also explores the integration of geospatial metadata with OGC services, demonstrating the potential for interoperability between RDF triples and OGC standards. The authors conclude that adding a semantic web layer with an ontology-based domain reference model can significantly improve data interoperability in EO.