In the summer this year I have joined the University of Copenhagen as a professor of international relations. As it is tradition in Denmark, I will deliver an inaugural lecture on the 30.11. In the lecture titled “Knowing the Sea. A Praxiography of Ocean Governance”, I revisit some of my past work on international practices and epistemic infrastructures to ask how we can make sense of contemporary ocean governance. Reviewing the past epistemic infrastructure of the oceans, and how concepts such as maritime security and the blue economy stand for a reproblematisation of ocean space, I discuss experiments in knowing and governing the oceans differently. I look at the spread of Maritime Domain Awareness as well experimentalist governing settings, such as UN Oceans, the Djibouti Code of Conduct, or the Contact Group on Piracy off the Coast of Somalia.