Blue bonds have emerged as a credible instrument for mobilising finance for sustainable ocean-related development, including marine conservation, climate resilience, and the broader blue economy. Cumulative global issuance reached US$ 15.25 billion by mid-2025, more than doubling year-on-year and registering the fastest growth across any sustainable bond category. Yet their scale remains elusive. At just 0.24 percent of the broader sustainable bond market, the blue bond asset class remains thin and fragmented.
Reaching the projected US$ 70 billion market by 2030 will require resolving supply- and demand-side constraints simultaneously. On the supply side, limited pipelines of investment-ready projects, institutional and technical capacity gaps, and elevated perceptions of credit risk continue to constrain the issuance of blue bonds. On the demand side, exclusion from major bond indices and weak benchmarking frameworks continue to limit investor participation, while substantial pools of domestic capital remain untapped. Unlocking their potential will require coordinated reforms in market design, risk mitigation, and local capital mobilisation.
The Blue Bond Market
Blue bonds are debt instruments whose proceeds are directed exclusively towards ocean-positive and marine projects. A subset of green bonds, they are issued by three types of entities: sovereign governments such as Seychelles and Fiji; multilateral development banks (MDBs) and financial institutions such as the Asian Development Bank (ADB), Nordic Investment Bank (NIB), and the Export-Import Bank of Korea (KEXIM); and corporations (such as Ørsted). These categories differ in how they structure and distribute risk. While sovereign issuers rely on fiscal guarantees, development banks leverage strong credit ratings to attract private capital at scale. Corporations, on the other hand, depend on market confidence and ESG (environment, sustainability, and governance) credentials.
Innovations such as DP World’s US$ 100 million issuance in the Middle East and North Africa (MENA) region in 2024, and Indonesia’s outcome-linked coral bond, are beginning to turn the tide. Geographically, while the Asia-Pacific (APAC) region has historically dominated blue bond activity, 2025 saw notable issuances across Latin America and the Caribbean, North America, Europe, and by supranational institutions. This growing regional diversification suggests a gradual broadening of market participation and issuer engagement.
Supply Side Problems
Despite growing momentum in ocean finance, the supply side of sovereign blue bond markets in the Global South remains severely constrained. Three interconnected problems stand out.
I. Limited Pipeline of Bankable Projects
Blue bonds require proceeds to be directed toward verifiable ocean-positive activities. However, structuring these activities into investment-ready projects demands significant technical capacity and upfront capital that emerging economies may lack. A bankable blue bond project needs to demonstrate robust implementation and governance capacity, as well as transparent monitoring, reporting, and verification (MRV) systems that demonstrate measurable environmental outcomes to satisfy due diligence requirements. Such a shortage of projects to absorb capital limits the effectiveness of blue bonds as an instrument.
II. Institutional and Technical Capacity Constraints
Issuing a blue bond demands considerably more expertise than conventional debt. For example, it requires adherence to use-of-proceeds frameworks, impact monitoring systems, and reporting standards benchmarked against the International Capital Market Association’s (ICMA) standards or the Climate Bonds Initiative taxonomy. These demands apply equally to sovereign governments, port authorities, and private-sector borrowers. The Seychelles’ blue bond illustrates both the potential and the ceiling of this model: it was achievable only through a US$ 5 million World Bank partial guarantee and a US$ 5 million Global Environment Facility (GEF) concessional loan, which together reduced its borrowing cost from 6.5 to 2.8 percent. This level of external scaffolding is not replicable at scale without a more systematic multilateral architecture.
III. Credit Constraints and Market Access
Across the Global South, both public and private borrowers either carry sub-investment-grade profiles or lack the credit ratings needed to access international capital markets independently. For corporates and subsovereign issuers—such as fishing enterprises, aquaculture firms, and port operators—barriers are compounded by limited collateral and shallow domestic capital markets. MDBs, with stronger ratings and greater project aggregation capacity, are natural near-term issuers, but their involvement remains a bridging mechanism rather than a final solution.
The Demand Side Gap
The demand side faces the problem of sequencing: instruments generally precede the conditions needed for their absorption, creating a dynamic shaped not merely by investor preference or risk appetite, but by the institutional and market structures that determine how capital is allocated.
- Index Exclusion as Architecture, Not Preference
In emerging markets, passive investing—where investors track a market index rather than selecting individual bonds—has made index architecture critical. Indices favour large, liquid issuers, rendering smaller sovereign and sub-sovereign borrowers invisible to major capital flows.
Meanwhile, sovereign credit ratings cap what a borrower in a particular country can access. When global conditions worsen, a sovereign downgrade automatically restricts capital access for all domestic borrowers. Reforming issuance standards alone cannot resolve these barriers. Until both structural barriers are addressed, even well-designed blue bonds will remain out of reach for the investors best placed to absorb them.
- Untapped Pools: Mobilising Domestic Capital
Middle-income economies already have deep pools of patient, local-currency capital that could support blue bonds without the currency risk or benchmark constraints faced by foreign investors. Domestic capital exists, but sustainability bond markets tend to develop more slowly without sovereign issuance programmes and credible policy frameworks that encourage institutional investor participation.
Middle-income economies already have deep pools of patient, local-currency capital that could support blue bonds without the currency risk or benchmark constraints faced by foreign investors.
For example, Thailand’s consistent sovereign bond issuance has built credibility, drawing domestic institutions into ESG-integrated portfolios. Elsewhere, although similar institutional capital is available, mechanisms to channel it into sustainability bonds, including blue bonds, remain underdeveloped. African pension assets now exceed US$ 500 billion across Botswana, Kenya, Namibia, Nigeria, and South Africa. Recent Nigerian reforms could unlock US$ 600 million in alternative flows, while Chile’s private pension funds have demonstrated through infrastructure project bonds that domestic institutional capital can anchor labelled markets when appropriate policy frameworks are in place.
Solutions for Scaling
Resolving these supply and demand constraints requires coordinated action across taxonomy, market infrastructure, and capital mobilisation. The following interventions can address these gaps:
- Launch a Dedicated Blue Bond Index: In 2025, BNP Paribas’s pioneering private banking structured product combined a blue bond with an MSCI co-developed water and ocean equity index. However, no standalone, benchmark-grade blue bond index has been established to date. A dedicated index would open the asset class to institutional investors currently excluded by conventional passive investment mandates.
- Scale MDB Support for Corporate Issuers: The corporate pipeline is the most scalable near-term source of blue bond supply growth, but investment-grade pricing requires systematic credit support. ADB’s Blue Bond Incubator and the International Finance Corporation’s (IFC) partial credit guarantees could be actively deployed at South and Southeast Asian blue corporates, such as seafood exporters, aquaculture firms, and port operators, to build replicable financing architectures.
- Develop Domestic-Currency Instruments: Foreign currency debt exposes issuers to exchange rate risk. Local-currency borrowing reduces these vulnerabilities while strengthening emerging market resilience. The IFC-backed issuance of Thailand’s first baht-denominated blue bond demonstrates this potential by tapping deep domestic institutional demand.
Building India’s Blue Bond Framework
India offers a concrete case for how these solutions might be sequenced within a single emerging market context. India’s fisheries sector supports nearly 30 million livelihoods, and seafood exports reached US$ 7.16 billion in 2024–25. At the same time, the institutional foundations for thematic debt issuance are already emerging through GIFT City’s sustainable finance ecosystem. In 2024, GIFT City’s International Financial Services Centres Authority (IFSCA) registered US$ 14 billion in green, social, sustainability, and sustainability-linked bonds.
A vast gap exists between the current scale and the actual financing needs of ocean-dependent developing economies. Bridging it will require significant interventions in taxonomic clarity, institutional commitment, and indexing to enable blue bonds to serve the Global South at scale.
India thus needs a dedicated blue finance category tailored to coastal resilience, sustainable fisheries, marine logistics, and ocean-linked climate adaptation. SEBI and the National Bank for Financing Infrastructure and Development (NaBFID), whose statutory mandate includes developing bond markets for long-duration infrastructure finance, could jointly develop a standalone blue bond framework with eligibility criteria and disclosure requirements calibrated to Indian coastal and fisheries assets.
Conclusion
Blue bonds are the only sustainable debt category to have grown without interruption since 2021. The recent doubling of their issuance signals that the market may finally be turning a corner. Yet a vast gap exists between the current scale and the actual financing needs of ocean-dependent developing economies. Bridging it will require significant interventions in taxonomic clarity, institutional commitment, and indexing to enable blue bonds to serve the Global South at scale.
Priya Noronha is a Research Intern at the Observer Research Foundation.
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