When one travels through rough terrain, maps come in handy. They also help researchers to study the complex organization of the brain. Scientists at the Max Planck Institute for Biological Intelligence have created a new set of maps for the zebrafish brain. They determined the activity of hundreds of genes with single-cell resolution and assembled the maps into an interactive atlas. The online resource supports researchers in finding their way around the brain of this vertebrate and provides new insights into neural structure and function.