The Great Bay Estuary of New Hampshire is the single largest estuarine system on the Gulf of Maine and its rich resources have attracted human settlement for millennia. With European settlement beginning in the 1600s, it became a locale of particular social and economic complexity. This period left a robust suite of tangible cultural heritage sites including standing architecture, buried archaeological sites, and early colonial graveyards. Yet due to its proximity to the watershed, this landscape and the cultural heritage that it holds, is highly threatened by sea-level rise brought on by climate change. In 2016, the UNH Department of Anthropology launched the Great Bay Archaeological Survey to inventory these vulnerable sites. It is a collaborative, community-based effort, drawing on evidence from historical documentation, traditional archaeological survey and excavation, and new mapping technologies. The result is an iterative process for an increasingly targeted program for identifying, documenting, and understanding at-risk early colonial sites in the Great Bay watershed. This panel explores the interconnections between these varied approaches. The first paper discusses the role of research in special collections and archives and how essential this work is in identifying significant cultural heritage sites before they are washed away. The second paper examines how new digital mapping technologies, including GIS, GPR and drones, are helping advance and expedite the study of these sites as they are found. The final paper explores the specific threats that sea-level rise poses to early colonial heritage sites and examines the hard questions that communities will face regarding what to preserve and what to let go.