Tourists might flock to Traverse City to soak up the waterfront views and play in the waves, but for Dr. Mark Holley, the most fascinating aspect of Grand Traverse Bay lies deep beneath its surface.

Holley teaches cultural anthropology and underwater archaeology at Northwestern Michigan College (NMC) and is chief archaeologist at the Grand Traverse Bay Underwater Preserve (GTBUP). He is also an instructor at the Nautical Archaeology Society in Northwestern Michigan (NASNMC). As part of a long-term research project initiated in 2007, Holley – along with his students – spends his days documenting the cultural resources that dot the bay's floor.

“Shipwrecks, ruins, submerged structures...our goal is to locate and preserve our archaeological heritage,” Holley explains.

At 32 miles long, 10 miles wide and up to 620 feet deep, Grand Traverse Bay is a sizable territory to cover. But thanks to NASNMC and GTBUP, as well as NMC's Great Lakes Water Studies Institute, an influx of technology, equipment and academic interest is helping lift the veil on the bay's mysteries.

Dive below the surface, Holley says, and here's what you might see:

Shipwrecks – The holy grail for divers and nautical archaeologists, shipwrecks can be found in abundance on Lake Michigan's murky floor. Locally, popular dive spots include the Metropolis schooner south of Old Mission Point, the tugboat The Tramp off Power Island and the towering freighter Francisco Morazon off South Manitou Island.

Using newly acquired sophisticated sonar equipment, NMC students recently mapped the bay's floor in high resolution, providing the first new bottom maps in 80 years. Among the discoveries of their hydrographic survey was the 1906 tugboat Lauren Castle, resting near Suttons Bay (of the more than 200 shipwrecks that have been documented by Mission Point Lighthouse keepers, only three have been discovered to date). Among the vessels haunting the bay that have yet to be located: remote-controlled drones from World War II, according to Holley.

Prehistoric Artifacts – Holley made a splash in the national scientific community in 2007 when he discovered a series of stones set in a circle 40 feet underwater in Grand Traverse Bay. One stone in particular stood out: It appeared to bear faint man-made carvings resembling a mastodon, an animal that went extinct 10,000 years ago. If authenticated by experts – a process Holley and his colleagues are still waiting on – the markings would constitute an ancient petroglyph, an invaluable historic find.

Other ancient Native American artifacts and settlements are still likely to be uncovered in the bay, Holley notes. That's because 8,000 years ago, the bay didn't exist – in its place instead was a valley, a probable home to human settlers.

Lumber Yards, Pipelines & Junk Piles – Clinch Park is a popular spot for sunbathers and swimmers, but dip just beneath the surface near the boat launch and you'll encounter one of the region's key attractions for divers: a vast graveyard of lumber, left over from the city's booming sawmill days. Relics from another past industry – the piping remains from the old power plant – also lure underwater explorers to downtown.

Holley's favorite place to dive, however, is an area known as the “Junk Pile” near Haserot Beach at the tip of Old Mission Peninsula. In the 1950s, teenagers attempted to create an artificial island on which to party by piling up items including small boats, a refrigerator – even a Ford Pinto.

“I've been diving all over the world, but I've never seen anything quite like it,” Holley says with a laugh.

While these and other cultural discoveries are important resources for understanding and protecting local nautical history, they represent only a tiny fraction of the bay's potential, according to Holley. "We haven't even begun to scratch the surface," he predicts.

What's important, Holley says, is that we keep looking.