Although the field of animal personality research is growing, information on sea lion personality is lacking. This is surprising as sea lions are charismatic, cognitively advanced, and relatively accessible for research. In addition, their presence in captivity and frequent interactions with humans allow for them to be closely observed in various contexts. These interactions provide a valuable and unique opportunity to assess dimensions of their personality. This study created a personality survey for captive California sea lions (Zalophus californianus) using a three-step approach that balances comprehensiveness and comparability to other species. Zookeepers (N = 43) at 5 zoological parks rated sea lions (N = 16) on 52 personality traits and 7 training traits. A principal components analysis (PCA) and regularized exploratory factor analysis (REFA) revealed three dimensions (Extraversion/Impulsivity, Dominance/Confidence, and Reactivity/Undependability). Each dimension was significantly correlated with at least one training trait. Pups and juveniles scored significantly higher on Extraversion/Impulsive than adults. No other age or sex effects were present on this or any other dimension. Sea lions are cognitively complex marine mammals that represent a valuable addition to the group of species in which personality structure and function has been studied. The unique behavioral and ecological characteristics of sea lions offer another vantage point for understanding how personality varies between disparate species.