TRAVERSE CITY -- Raindrops pelted and roiled scenic West Grand Traverse Bay's surface, but those aboard the Northwestern didn't mind.
They cared more about what undiscovered treasures lurked beneath.
Northwestern Michigan College leads the first effort to map the bottom of Grand Traverse Bay in more than 80 years, and school officials this week used sonar technology to distinguish sand bars, rocky shoals, fish habitat, logs, plant growth and sunken ships.
It's the only Great Lakes locale where such high-resolution, water-mapping technology is used. Officials hope it leads to more efforts to study the floors of North America's freshwater inland seas.
"Our students will use this information for their studies on what's going on in the bay," said Hans VanSumeren, director of NMC's Water Studies Institute. "I think getting people excited about what's down there is important. It's not just about what's on the surface."
Officials are using side-scan sonar equipment on the Northwestern, NMC's research vessel, to capture imagery in a 1,000-foot swath as they move back-and-forth across the bay. The technology allows them to view outlined images from the bottom.
"To be able to tell people about what's in our Great Lakes is wonderful. We've never before seen the lake bottom like this," said Mark Breederland, Michigan Sea Grant's extension educator in Traverse City, and whose agency is assisting with the research.
Existing bay depth data stretches to the late 1920s. Modern sonar technology will provide updated, expanded information that can be used in environmental assessments, coastal management, bottomland studies, commercial navigation charts, fisheries research and tourism opportunities.
Data gathered as part of the research will be shared with agencies like the National Oceanic and Atmospheric Administration and catalogued on a public digital water library, VanSumeren said.