Citizen participation has become a focus as a means for increasing democratic legitimacy across a range of policy contexts, including marine governance. At national and sub-national scales, civil and 'stakeholder' participation in marine governance has become increasingly common. Benefits from participatory processes promised in the literature include the reduction of conflict between sectors, industries and/or communities (including the so-called 'social licence to operate'); social learning and community adaptation to changing marine ecosystems, conditions and new marine industries; increased social acceptance of decisions about shared use of marine ecosystems; and increased democratic legitimacy for decision-makers. In practice, however, empirical research in marine governance is pointing to the failure of participatory processes to achieve these aims, resulting in a continuation of contested outcomes and citizen disillusionment. Further, there are limited approaches to theorisation of participation in marine governance, constraining the ability of practitioners and researchers to explain or address these failures. In this thesis, I examined participatory norms and practices in marine governance to consider institutional limits that contribute to the problem of participatory governance failure, and to extend the theoretical underpinnings of marine governance research and practice. My research was designed as a mixed-method constructivist examination: an approach that is appropriate to address the complexity of discourses, norms and material practices. To shed new light on how we think about participation in marine governance, I adapted Hannah Fenichel Pitkin's seminal theory of democratic participation and representation. Pitkin established that 'participation' and 'representation' are intrinsically linked by three essential conditions: authorisation, dissent and exit, and accountability. Using this core element of Pitkin's theory as a 'lens of participation‚Äö-representation', I conducted a detailed analysis of how participatory principles and practices are constituted in marine governance, identifying the norms and implied political theory underpinning contemporary marine governance discourse. I found that marine governance research and practice is strongly influenced by norms from participatory democracy theory ‚Äö- what I refer to as the social-ecological systems (SES) paradigm. I argue that the ecosystem framing of the SES paradigm pushes participatory democracy theory into new conceptualisations of the polity ‚Äö- as defined by the ecosystem rather than the nation-state ‚Äö- and recasts political processes as social interrelations built on social capital. I also found that this reframing of political structures is largely unarticulated and incomplete, and as a result creates limitations in the institutional and material practices of marine governance. To test this conceptual framing, I turned to empirical practices to see if and how the precepts of the SES participation norm and the lens of participation‚Äö-representation manifest in practice. Through two case studies I found that participatory initiatives lacked democratic legitimacy in the terms established by the conceptual frame (the lens) and that the SES discourse, norms and practices were prevalent and implicated in the institutional and legitimacy limitations. The conceptual frame I developed in this research proved to be relevant and useful for analysing the limitations of the two case studies I examined. The quantitative basis of my analysis of marine governance discourse means that these case study findings are likely to be relevant to other instances of participatory marine governance. On this basis, I suggest the conceptual lens is sound and makes a useful contribution to the work of articulating the theoretical underpinnings of the SES paradigm. Finally, I suggest this work supports the development of a richer understanding of democratic institutional legitimacy and reflective practice in marine governance as we move through significant social, political and ecosystem changes.