Papua New Guinea's first deep-sea mining project, once touted as the first of its kind in the world, now appears to be "dead in the water." The mining company behind it has been liquidated, the mining equipment has been rendered obsolete, and the host government has been made to look foolish for supporting the enterprise. This paper examines the application of two concepts-that of the "resource frontier" and that of the "actor-network"-to reach an understanding of the history of this apparent failure. By elaborating on the additional concept of a "network junction," it seeks to show how arguments about the feasibility or fallibility of this particular project, and deep-sea mining proposals more broadly, have been related to arguments about a range of other issues in which scientific and technological uncertainties are associated with environmental and social impacts or environmental and political risks. Instead of seeking to explain the failure of this project by reference to the attributes of a specific type of maritime resource frontier, the paper shows how the articulation of different policy networks creates the appearance of a frontier in which human and non-human actors have combined to produce a variety of unpredictable and open-ended outcomes. From this point of view, the history of this project's failure cannot simply be read as the outcome of a contest between two groups of human actors with clearly defined interests or ideologies, nor does it necessarily spell the end of the policy network in which this project has been embedded.