Transport system is one of the critical systems in all societies. Despite growing interest towards supply chain vulnerabilities and the meaning of critical infrastructures to societies, analysis on vulnerabilities related to maritime transports in a security of supply context has not gained much interest. However, any failure in transports can have very disruptive consequences not only to companies’ supply chains but also to national supply security and daily life of people. With this paper, we contribute to analysis on mitigation strategies of critical industries towards transport disruptions. Our case study concentrates on impacts of a port closure due to a strike in Finland in 2010 and companies’ strategies to manage their operations during the strike, and we draw conclusions to the general structure of mitigation strategies towards logistic vulnerability.