The Great Lakes Bottom Mapping Working Group (BMWG) is a network of agencies, organizations and citizens with an interest in some aspect of lake bottom ecosystems, including for purposes of management, research, historic preservation, recreation, and navigation. Any individual or organization can join.

The group was established to facilitate communication among stakeholders across the region, promote coordination of new data collection, and serve as a resource for information and data on bathymetry, bottom habitats, coastal topography and benthic ecosystems. The working group  is led by a diverse bi-national Steering Committee and is organized according to the principles of Collective Impact.

The formation of the working group was motivated by the recognition that high-resolution information about lake bottom environments was largely missing from the Great Lakes to the detriment of the Great Lakes Water Quality Agreement (GLWQA) and national efforts in Canada and the United States including the Great Lakes Restoration Initiative.

The goal of the Bottommapping Working Group is to promote the collection, harmonization, sharing, and use of continuous high-resolution maps and data about Great Lakes bathymetry, geology, habitat, and cultural resources.