Secondary ports draw less attention than major ports. Their commercial influence doesn't stir up much political debate, nor does it attract significant interest from researchers. However a detailed analysis demonstrates that secondary ports may significantly impact the efficiency of supply chains. Many industries rely on secondary ports as essential logistics links, which give them access to overseas markets and thus enhance their competitiveness. This paper stresses that these secondary ports offer short sea shipping services and also deep sea shipping services. It examines two French agribusiness supply chains in Brittany, and highlights how supply chain managers can derive decisive benefits from transit via secondary ports.