The integration of digital finance into marine and seaside economies offers transformative potential to foster sustainability, equity, and economic growth. This chapter explores the role of financial technology (FinTech) in addressing the unique challenges faced by coastal and marine industries, including resource depletion, economic instability, and socio-environmental disparities. It highlights how innovations like blockchain, artificial intelligence (AI), and mobile financial platforms can enhance financial inclusion for coastal communities, streamline investment in sustainable marine projects, and promote transparent governance. Through case studies and data-driven analysis, the chapter investigates global best practices where digital finance has enabled resource optimisation, resilience in the face of climate change, and support for blue economy initiatives. By examining the interplay of technology, finance, and sustainability, this chapter aims to provide actionable insights into leveraging digital finance for building resilient and equitable marine ecosystems, contributing to a sustainable blue economy.