This article analyzes the history of conflict and cooperation on the river Scheldt. Dutch-Flemish relations over the shared Scheldt estuary go back for centuries. Only in the past 10 years has there been intensive negotiation on a joint vision for its future which takes the form of a cooperative multi-stakeholder platform incorporating public, private and NGO representatives. Yet, relations have not always been cooperative; negotiations have been tense at times. After discussing the merits of a learning- versus a fighting-oriented analysis and capturing its dynamics in a TWINS matrix, this study proposes an approach that combines collaboration with competition, or learning and fighting. The case analysis finds that relations were often conflictual and cooperative simultaneously and warns against undue optimism about the multi-stakeholder process on the Scheldt estuary.