Policy projections and recent research suggest that large numbers of irregular migrants from sub-Saharan Africa will continue to attempt to make their way to Europe over the next few decades. In response, European countries have made and continue to make significant investments in information campaigns designed to discourage irregular African migration. Despite the ubiquity of these campaigns, we know relatively little about potential migrants' prior knowledge and beliefs. To what extent are potential migrants actually misinformed about the migration journey and destination countries? We bring representative survey data collected in Benin City, Nigeria — a center of irregular migration — to bear on this question. Three key insights emerge. First, potential migrants are better informed about destination contexts than is commonly assumed, and if anything appear to underestimate the economic benefits of life in Europe. Second, they are relatively less well informed about specific risks and other features of the irregular migration journey. Third, we find evidence of optimism bias. Respondents are generally hopeful when asked about Nigerian irregular migrants' prospects of being able to reach and stay in Europe, but they are especially optimistic when asked about their own chances. Taken together, these findings suggest that existing migration-related information campaigns, and with them a central component of migration policies in countries across the Global North, rest on shaky foundations. Most problematically, our study suggests that campaigns risk becoming misinformation campaigns, particularly when they suggest to potential migrants that they are overestimating the benefits of living in Europe.