This article discusses the development of second ship registers and their interconnections to the policy idea of maritime clusters. Through a narrative of the contemporary history of Danish maritime policy, the article shows how these apparently different policy measures were closely related and together constitute a coherent framework based upon specific values, views of cause–effect relationships, and perceptions of major challenges and their context. Danish maritime policy provides an excellent case for the study of the contemporary history of maritime policy-making. Denmark was among the first of the traditional shipping nations to set up a second register, and the concept of maritime clusters became part of Danish maritime policy before it emerged as a construct in European Union maritime policy. We provide detail on the unfolding of some of the most important recent events in Danish maritime policy and highlight its development as a process of learning that involves the prolonged drafting and fine-tuning of statements and ideas, and the borrowing and adjustment of policy ideas developed elsewhere.