What happens when a distant colonial power tries to tame an unfamiliar terrain in the world's largest tidal Δ? This history of dramatic ecological changes in the Bengal Δ from 1760 to 1920 involves land, water and humans, tracing the stories and struggles that link them together. Pushing beyond narratives of environmental decline, Bhattacharyya argues that 'property-thinking', a governing tool critical in making land and water discrete categories of bureaucratic and legal management, was at the heart of colonial urbanization and the technologies behind the draining of Calcutta. The story of ecological change is narrated alongside emergent practices of land speculation and transformation in colonial law. Bhattacharyya demonstrates how this history continues to shape our built environments with devastating consequences, as shown in the Bay of Bengal's receding coastline.