Hello MARMAMers, We are happy to share our open access article in Data in Brief with a set of bottlenose dolphin sightings collected by volunteers throughout Chesapeake Bay over 5 years. *Title*: Chesapeake DolphinWatch sightings data (2017–2022): Citizen science reports of bottlenose dolphins observed in the Chesapeake Bay, USA *Authors*: Lauren K. Rodriguez, Jamie C. Testa, Kirsten Silva, Helen Bailey *Abstract*: Atlantic bottlenose dolphins are extensively studied, though little has been published regarding their occurrence patterns in the large and highly urbanized estuary of the Chesapeake Bay, USA. To address this knowledge gap, the Chesapeake DolphinWatch project was initiated in the summer of 2017. Utilizing a citizen science (also known as volunteer science) methodology, members of the public were encouraged to report dolphin sightings through a specialized mobile (iOS and Android) and web-based (https://chesapeakedolphinwatch.org) application. This approach ensured extensive, yet non-invasive and financially-efficient, data collection. The dataset presented here includes bottlenose dolphin sighting reports submitted to Chesapeake DolphinWatch by citizen scientists over five years; from June 28, 2017 through December 9, 2022. These data have been quality checked by researchers at the University of Maryland Center for Environmental Science's (UMCES) Chesapeake Biological Laboratory (CBL) in Solomons, Maryland (USA). This dataset holds potential for various applications, such as analyzing the spatiotemporal patterns of dolphin presence within the Chesapeake Bay, investigating the behavior and movements of bottlenose dolphins in the mid-Atlantic, and serving as a comparative benchmark for studies in other estuarine systems. By integrating community engagement with technological platforms, the provided data showcases the invaluable role of citizen science in advancing marine ecological research. *DOI*: https://doi.org/10.1016/j.dib.2024.110368 Though it is not newly published, we hadn't yet shared it with the community on this listserv. We hope students and researchers who work with marine mammals and citizen science will find it useful. Warm regards, *Jamie C. Testa (*she/her <https://www.mypronouns.org/she-her>) Project Coordinator for Chesapeake DolphinWatch <https://www.umces.edu/dolphinwatch> University of Maryland Center for Environmental Science Chesapeake Biological Laboratory <https://www.umces.edu/cbl> JCTesta@umces.edu