Debt is the lending or borrowing of funds, at scales ranging from micro-finance loans (typically up to US$50,000) to large-scale corporate loans (US$100 million or more). Debt instruments may be called loans, bonds or notes, among other things.Debt is a low-risk investment for the lender, whose risk is limited to the non-payment of the principal and interest on the loan. However, to reduce this risk, some lenders may require a Investment models \ 7borrower to ‘secure’ the loan by pledging assets as collateral against it. Mortgages are the most common example of this (for example, for residential properties); however, it is challenging for private organisations to identify assets for collateral in ocean-based development projects, given the public ownership nature of most ocean and nearshore real estate. This is not necessarily a concern for governments (as ‘holders’ of these and many other assets), but sovereign borrowers also need to consider their budgetary debt position.In line with its low risk, debt can also have a low return to the lender, limited to the interest that it is agreed the borrower will pay. This may be a fixed rate of interest or a variable rate that may fluctuate over time. Although private sector lenders usually set interest rates based on market conditions, some public organisations (such as MDBs) provide loans at reduced (or concessional) interest rates.Apart from any terms set when the lender and borrower enter into the contract, lenders generally have little influence over the investment. For green loans and bonds, the terms may include compliance with green or sustainable standards. For example, green bond standards limit the use of the borrowed funds to particular environmental projects and also apply conditions on how the funds are managed in the meantime. Green bonds (and related thematic bonds such as blue and SDG bonds) are very attractive to investors and are usually oversubscribed.