Site-based citizen science occurs when volunteers work with scientists to collect data at particular field locations. The benefit is greater data collection at lesser cost. Yet difficulties exist. We developed ScienceCaching, a prototype citizen science aid designed to mitigate four specific problems by applying aspects from another thriving location-based activity: geocaching as enabled by mobile devices. Specifically, to ease problems in data collection, ScienceCaching treats sites as geocaches: Volunteers find sites opportunistically via geocaching methods and use equipment and other materials pre-stored in cache containers. To ease problems in data validation, ScienceCaching flags outlier data as it is entered so that on-site volunteers can be immediately check and correct data. Additionally, other volunteers are directed to that site at a later time for further readings that provide data redundancy. To ease volunteer training, ScienceCaching directs volunteers to training sites on an as-needed basis, where they are taught and tested against known measures. To ease volunteer coordination, ScienceCaching automatically directs volunteers to particular sites of interest, and real-time communication between volunteers and scientist is enabled as needed. We developed ScienceCaching primarily as a technology probe—a working but quite limited system—to embody these ideas and to evaluate their worthiness by eliciting reactions from scientists involved in citizen science. Scientists saw many opportunities in using fixed location caches and geocaching techniques to aid citizen science. Yet they expanded the discussion. Amongst these, they emphasized practical concerns that must be addressed, and they argued that future systems should carefully consider the role of the social experience—both the “online” experience and the shared physical experience of visiting sites.