Climate change has forced governments to take actions in order to preserve, among other things, marine biodiversity, whose survival is threatened by pollution and human activities. The so-called blue economy – which represents a peculiar form of green economy – covers a broad group of activities related to oceans and seas which must be carried out in a sustainable and healthy way. In this economy, a main role is played by blue bonds, a form of thematic bond, where the issuers commit themselves to use the capital raised to support investments in blue economies and projects that pursue United Nations Sustainable Development Goal 14. One of the main features necessary to pursue that aim is the transparency of the information the issuer discloses to the investors. The new Regulation (EU) 2023/2631 certainly provides useful tools to foster transparency in green (and blue) economies in terms of information to be disclosed in order to tackle greenwashing risks, but, at the same time, it presents features that could be better specified and improved and that could better pursue that aim if harmonized on a European level.