The advent of the Web has brought an unprecedented amount of information together with a large, diverse set of users. Online users are performing a wider variety of tasks than ever before. For example, not only is the Web being used to search conventional databases like Lexis/Nexus, it is also being used to broker Beanie Babies® . Today’s common information seeking metaphors (i.e., keyword search and hypertext) cannot be expected to support all these new tasks well. Our research investigates new metaphors for online information seeking tasks. We characterize a new user behavior called opportunistic exploration and show how it is significantly different than both browsing and searching. A novel visual metaphor for opportunistic exploration, an aquarium, is presented. The aquarium allows users to explore a large corpus at any level of granularity. Keywords Information retrieval, visual navigation, adaptive hypermedia, visual metaphor, browsing, searching