This book explores how speculative thinking is shaping how we relate to our entangled social, mental, and environmental ecologies. It examines how speculative philosophies and concepts are changing geographical research methods and techniques, whilst also developing how speculative thinking transforms the way human, non-human, and more-than-human things are conceptualised in research practices across the social sciences, arts, and humanities. Offering the first dedicated compendium of geographical engagements with speculation and speculative thinking, the chapters in this edited collection advance debates about how affective, imperceptible, and infra-sensible qualities of environments might be written about through alternative registers and ontologies of experience. Organised around the themes of Ethics, Technologies, and Aesthetics, the book will appeal to those engaging with architecture, Black political theory, fiction, cinema, children's geographies, biotechnologies, philosophy, rural studies, arts practice, and nuclear waste studies as speculative research practices appropriate for addressing contemporary ecological problems. Chapters 1, 3 and 4 are available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.