The Thunder Bay National Marine Sanctuary (TBNMS) encompasses 4,300 mi² of Lake Huron off the northeastern shore of Michigan. Much of the lakebed in the sanctuary was mapped prior to 1950 and therefore those data suffer from multiple deficiencies by today’s standards. New technologies can efficiently provide more accurate and resolved depths, and also characterize the substrate types of the lakebed. However, the sanctuary is vast and the entire area cannot be mapped in a short timeframe. Smaller areas must be identified to address the most urgent priorities. The Thunder Bay National Marine Sanctuary (TBNMS) encompasses 4,300 mi² of Lake Huron off the northeastern shore of Michigan. Much of the lakebed in the sanctuary was mapped prior to 1950 and therefore those data suffer from multiple deficiencies by today’s standards. New technologies can efficiently provide more accurate and resolved depths, and also characterize the substrate types of the lakebed. However, the sanctuary is vast and the entire area cannot be mapped in a short timeframe. Smaller areas must be identified to address the most urgent priorities.