The latest historic place in Minnesota is one you can visit only with scuba gear.

A rare wooden model barge from 1879 that was owned by railroad tycoon James J. Hill — and still rests where it sank in Lake Minnetonka — was recently approved for placement on the National Register of Historic Places.

The Wayzata Bay wreck is the oldest known that an archaeological research team has found on the bottom of the metro area’s largest lake, and the first wreck on Minnetonka to get on the National Register. It’s also the best preserved of three model barge wrecks in the United States.

“Out of the whole country, we’ve got the one that’s intact,” said Ann Merriman, who runs the nonprofit Maritime Heritage Minnesota with her husband, Christopher Olson. “There were hundreds and hundreds of these that didn’t survive. This is the one by which everyone will now compare.”

The wreck is in good condition thanks to Lake Minnetonka’s cold fresh water and muddy bed, which helps preserve wooden structures. Encased in silt and 85 feet long, the barge remains largely intact about 40 feet below the water surface. The model barge, so-called because its pointed ends were modeled after a steamboat bow, was used by Hill to transport cordwood on the lake.

“Without that kind of watercraft, the lake wouldn’t look like it would today — for good or bad,” Merriman said.

But because it was used by everyday workers, it didn’t attract the same attention as steamboats or other boats, and little was recorded about it. Merriman and Olson tracked down its story with the help of old newspaper clippings about a barge that sank in a “lively” September storm in 1879.

Maritime Heritage Minnesota nominated the wreck for the National Register, funded by a state Legacy historical and cultural heritage grant. While most historic sites are buildings or places you can easily visit, Minnesota has 15 shipwrecks on the register.

“This one really stood out,” said David Mather, National Register archaeologist with the Minnesota Historical Society. “It just sank and sat there in the undisturbed setting for years. It’s really remarkable.”

The new designation will help raise public awareness, he said, adding that “a lot of people don’t know archaeology sites exist in Minnesota.”

Merriman and Olson are the only underwater archaeologists in Minnesota. In 2011, they started a long-term project to survey Minnetonka, a lake with a legendary history of boating and sailing.

Before they started, there were six known wrecks in the 14,000-acre lake. Olson and Merriman have identified 57 more, tracing each one to the craft’s owner, builder or those involved in the sinking, either intentional or accidental — from motorboats to a passenger steamboat that sank in 1899, and even a 1936 Plymouth sedan.

Now they’re in their fifth year of the project. Make no mistake, they aren’t treasure hunting; they don’t raise the wrecks, and looting is illegal.

Rather, they liken the lake to an underwater museum, carefully identifying wrecks and spending hours poring over historical records and old newspapers to research each one’s story.

“These are the only tangible pieces of our history on Lake Minnetonka,” Merriman said. “We do value that history.”