Although it is well known that microbial cells can exhibit sophisticated cooperative behaviour, none of the recent advancements in geomicrobiology has been so perplexing as the proposal that microbial populations are capable of fast, electrical communication over centimetre scale distances. This metabolic tour-de-force was recently documented from laboratory incubations with marine sediments. Clearly, the phenomenon is so thought provoking, and its consequences are so far reaching, that independent verification is absolutely needed. Recently, my research group has collected strong evidence that long-distance electron transport is not merely a laboratory phenomenon, but that it effectively happens under in situ conditions in marine sediments. These observations open a broad avenue for new research, since at present, we no understanding of the prevalence of long-distance electron transport in natural environments, let alone, its impact on biogeochemical cycling. In response, this ERC project proposes an in depth investigation into long-distance electron transport in aquatic sediments: when and where does it occur, which redox pathways and microbial players are involved, what is the effective mechanism of electron transfer, and what are its biogeochemical implications. Clearly, this idea of long-distance electron transport would add a whole new dimension to microbial ecology, radically changing our views on microbial cooperation. Yet, the consequences for carbon sequestration and mineral cycling in sediments and soils could even be more astounding, allowing an unprecedented flexibility in redox pathways. Since the same type of extracellular electron transport is at work in engineered systems like microbial fuel cells, it could also improve our understanding of such biotechnological applications.