The central problem of the 21st century, argues Stefan Helmreich, will be the “water line,” where longstanding patterns of inequality and discrimination intersect with growing threats to life itself. The rallying cry “Water is Life,” voiced by environmental and anti-extractive movements throughout the Americas and beyond, invokes the water line to build new political coalitions for demanding environmental and climate justice. This course asks students to critically examine and experientially engage with the water line as it has taken shape in Costa Rica and Latin America in order to understand how such coalitions work to counter climate crisis and its disproportionate effects on poor, Indigenous, and Black peoples. Together we will survey the problems that humans and other living beings increasingly face in accessing water, identify the structures and processes that limit access, explore new ways of relating to water, and imagine how we might act on and through these relations. Held at the Las Nubes Eco-campus in Costa Rica, the course involves site visits to bodies of water near the campus and conversations with activists and communities engaged in water politics.