What Thailand's Maya Bay teaches us about the missing link in blue finance

A few years ago, Maya Bay on Thailand's Ko Phi Phi Le was receiving an estimated 5,000 visitors a day, with roughly 200 boats anchoring in the bay daily. The national park around it earned 555 million baht (around US$16 million) from visitors in a single season, more than any other national park in Thailand. Yet the reef that drew them was collapsing: Marine biologists found that 50 to 80 percent of the surrounding coral reefs had been damaged by boat traffic, pollution, and overcrowding. In 2018, Thailand did something few tourism-dependent economies would dare: it closed the Bay. Coral began to regrow, and blacktip reef sharks returned in spectacular numbers for the first time in years. When Maya Bay reopened in 2022, visitor numbers were capped and management measures strengthened. Maya Bay demonstrates a simple point: a healthy ocean creates benefits – jobs, GDP, food security – that people rely on every day.The question is how those benefits can help support the long-term sustainability of the resources that generate them. A return no one collects Water and marine ecosystems underpin tourism, fisheries, food and water security, and coastal protection. The ocean economy alone generated US$2.6 trillion in value added in 2020, and more than three-quarters of its growth since 1995 came from Asia and the Pacific. Coral reefs reduce annual expected flood damage by more than US$4 billion globally. Without reefs, damage from a one-in-100-year storm could rise by 91 percent. These assets are under growing pressure. During the 2024 marine heatwave, extensive coral bleaching affected reefs across the Gulf of Thailand. Hotels, dive operators, ports, utilities, coastal property owners, and their insurers all lose out when these assets are degraded and destroyed. Conversely, they directly benefit from a healthy ocean. The result is a familiar disconnect: economies depend on these assets, but only a small share of that value finds its way back to the assets that make it possible. Why investment isn't flowing The blue economy could be worth an estimated US$5.5 trillion a year by 2050. Despite its importance to climate resilience, food security, and jobs, the Sustainable Development Goal focused on life below water (SDG 14) remains the least-funded of all 17 SDGs, receiving less than 1 percent of total SDG finance. Too much natural capital is unpriced, which means it isn’t being paid for. In water, roughly 91 percent of spending in developing countries comes from the public sector and less than 2 percent from the private sector. But even this public spending is mostly off-budget and invisible to Ministers of Finance. The blue bond market reflects a similar dynamic. Investor interest is growing, with global blue bond issuance surpassing US$15 billion by mid-2025. However, blue bonds account for only around 0.25 percent of the global sustainable bond market, which had reached more than US$6 trillion in cumulative issuance by March 2025. Economic value does not automatically translate into an investable opportunity. Private capital still needs clear revenue streams, manageable risks, and structures that can be replicated at scale. From environmental value to investment opportunity Morocco's aquaculture sector shows how this can change. The country is expanding sustainable aquaculture, helping create the conditions for private investment in, for example, climate-resilient seaweed production. The sector is expected to reach 300,000 tons of production and create 30,000 jobs over the next decade. More broadly, aquaculture is projected to become a US$1.5 trillion investment opportunity globally by 2050. Opportunities are emerging beyond the coast as well. In Brazil, São Paulo’s private water utility, SABESP's blue-finance program mobilized financing from seven international commercial banks to support wastewater collection and treatment in the Tietê River basin. The financing supports the Integra Tietê program, an effort to improve water quality in a river system stretching more than 1,000 kilometers and supporting over 20 million people. By bringing commercial lenders into a sector traditionally dominated by public funding, the transaction illustrates how environmental goals can begin to attract private capital when linked to activities with clear revenue streams and measurable results. The Pacific offers another perspective. Through the Parties to the Nauru Agreement, eight Pacific island countries and Tokelau transformed the management of one of the world's largest sustainable tuna fisheries. Tuna revenues increased from about US$60 million in 2010 to around US$500 million annually, while employment in the industry grew by 44 percent between 2015 and 2022. Science-based fishing limits and full observer coverage have helped ensure that those gains are built on a sustainable resource base. From pioneers to markets In Southeast Asia, examples of blue-finance innovation are growing. The challenge is moving from individual transactions to a market capable of mobilizing capital at scale. The scale of what's needed is hard to overstate: Asia and the Pacific will need about US$53 billion a year for water and sanitation alone through 2030. Meeting needs of that magnitude will require more funding and more finance. What is often missing are the practical mechanisms that help investors identify projects, assess risks, and understand how environmental outcomes connect to financial performance. And it will require a pipeline of bankable projects in which to invest that finance. Across the World Bank Group, efforts are increasingly focused on addressing these market constraints. Through initiatives such as Water Forward, governments are working to make water systems more investable and resilient. In Asia and the Pacific, IFC's Beacon for Blue (B4Blue) applies a market-creation approach to blue finance, working across water, plastics, aquaculture, and shipping to move blue finance from pioneering transactions toward broader market adoption by addressing gaps in standards, project pipelines, capacity, and market intelligence. Together, these efforts are helping lay the foundations for a more mature blue-finance market and creating the conditions for private capital to participate on a greater scale. Collecting the ocean's dividend Maya Bay's recovery offers more than a conservation success story. It highlights both the benefits that healthy water and marine ecosystems can generate and the challenge of sustaining them over time. If the future of blue finance lies anywhere, it may lie there: in creating practical pathways for private capital to participate more systematically in the assets, services, and infrastructure that healthy water and marine resources represent.