Finland is the only country in the world where all ports freeze over during a typical winter. Over the century 1878–1978, Finland developed a winter-seafaring system that broke the winter isolation and eliminated seasonal variation in shipping. By using diverse archival sources, we deconstruct the dominant narrative of Finnish winter seafaring through which national as well as technological development is often presented as natural, inevitable and straightforward. We reinterpret the Finnish winter navigation system as a tangible, historical experience and show that technological solutions in this domain cannot be understood outside the context of a decades-long process of nation-building. Finally, we argue that winter navigation became a central imaginary for Finland as a western, industrial and modern nation. As such, the Finnish winter-seafaring system presents a case of technological nationalism in which a small, peripheral country sought to integrate itself into a modern international order.