According to the Porter hypothesis, regulations on environmental emissions under certain conditions can promote eco-innovation. This is why the technological innovation systems (TIS) theory sees regulatory pressure as a major system function critical in the take-off phase. In other words, the design and timing of any regulation may be decisive for the regulatory outcome. The research seeks to provide empirical evidence on how the Baltic Sea Sulphur Emission Control Area (SECA) has impacted the technological innovation system within the Baltic Sea Region maritime sectors. The results (1) show that regulatory compliance gave a knowledge development that has made it possible for clean-tech companies to engage in entrepreneurial activities that created new markets, (2) empirically support the TIS theory and the Porter hypothesis, and (3) provide qualitative evidence on how businesses see environmental regulation. The innovation system for ship sulphur emission abatement.