Accessible Ocean Tourism – Opening the Blue Frontier: Why Accessibility Matters in Ocean Tourism This article examines Accessible Ocean Tourism as a critical yet underdeveloped pillar of sustainable tourism and the blue economy. It conceptualizes the “Blue Frontier” as both an economic opportunity and a social responsibility, emphasizing accessibility as a prerequisite for equitable participation in ocean-based tourism for persons with disabilities and other marginalized groups. Drawing on international accessibility frameworks, tourism policy developments, and applied practice examples, the research analyzes persistent barriers in ocean and coastal tourism, including inaccessible infrastructure, limited adaptive equipment, insufficient staff training, fragmented information systems, and weak integration of accessibility into tourism planning and regulation. The paper highlights the role of human capital, digital skills, inclusive and disability-inclusive design, and cross-sector collaboration in operationalizing accessible ocean tourism. Positioned within the commitments of the UN 2030 Agenda and the principle of “Leaving No One Behind,” this work argues that Accessible Ocean Tourism is not a niche market but a core pillar of resilient, inclusive, and sustainable coastal destinations. Authorship and Provenance Statement: This work is original and authored solely by Elsie Gabriel, Independent Researcher – Accessible & Sustainable Tourism. The conceptual framework, abstract, analysis, and written content were independently developed by the author. This record establishes authorship, intellectual contribution, and timestamped provenance via DOI and ORCID linkage.