Grand Lake St. Marys features three lighthouses and 52 miles of shoreline. (Credit: WYSO)

By Ken Drenten

Ohio’s largest inland lake perhaps has the biggest identity issue of all of the state’s recreational lakes. Is it called “Grand Lake” or “Grand Lake St. Marys?”

Over the years, the lake in Mercer and Auglaize counties has been called Grand Reservoir, Lake Mercer, Lake St. Marys and Lake Celina before being declared Grand Lake by the U.S. Geological Survey. The Ohio Department of Natural Resources officially names it Grand Lake St. Marys.

Fortunately, so there’s much to do for a day, a weekend or an entire summer around this lake in western Ohio that its reputation is well-known for fun and relaxation.

Grand Lake St. Marys has 13,500 acres of water surface area and 52 miles of shoreline, but it is shallow, with an average depth of only 5-7 feet. Constructed by men and animals in the 1830s and 1840s to feed the Miami and Erie Canal, at one time the lake was the world’s largest man-made lake.

Late in the 19th century oil was discovered in the area, and more than 100 oil derricks were set up in the lake in the 1890s, making it the first site for offshore oil drilling. The lake became home to one of Ohio’s first state parks in 1949.

Grand Lake St. Marys State Park in St. Marys (a charming canal town at the eastern shore of the lake) is just the start, with camping, cabins, swimming, boating, picnicking, hiking and many other outdoor pursuits. Fishing for bass, yellow perch, crappie, bluegill is popular; the lake is open to unlimited horsepower boating and has eight boat ramps.

The area is also a major migration route for water birds including heron, cormorant, egret, osprey, speckled geese and even pelicans. Nearby the lake is the Miami and Erie Canal, offering opportunities for hiking, biking and exploring. And did you know that this expansive, unique lake has not one, but three fully functioning lighthouses?

Map credit: Ohio Department of Natural Resources, Ohio State Parks

When you’re in the mood for other kinds of entertainment, the lake’s Boardwalk Village has everything you need. This all-in-one lakeside experience in Celina (at the western side of the lake) offers dining, entertainment, lodging and recreation.

Venturing out from the lake area into the surrounding countryside and small towns offers a wide variety of restaurants, museums, shops, wineries and breweries, coffee shops, ice cream shops, parks and points of interest.

The Armstrong Air & Space Museum celebrates the legacy of NASA Astronaut Neil Armstrong, the first human to step foot on the Moon. Numerous artifacts from Armstrong’s life and career as well as space-related exhibits and interactive displays are within the museum. 500 Apollo Drive, Wapakoneta, (800) 860-0142.

The Bicycle Museum of America  has more than 200 bicycles on display and 800 in its total collection.  You can embark on a guided or self-guided adventure to learn more about the history of the bicycle from its very beginning in 1816 through modern times, and how the bicycle helped shape the American landscape through innovation and design. 7 W. Monroe St., New Bremen, (419) 629-9249.

Fort Recovery Museum tells the story of St. Clair’s Defeat in 1791 and the Battle of Fort Recovery in 1794, two important events in Ohio’s frontier history. A reconstructed fort, blockhouses, log cabins, Native American tribal artifacts and the 101-foot-tall Fort Recovery Monument are part of this site. 1 Fortsite St., Fort Recovery, (800) 238-8920.

To read about all there is to do in the Grand Lake St. Marys region and obtain a tourism guide, go to the Grand Lake Region website. You can also visit or call the Greater Grand Lake Region Visitors Center, 900 Edgewater Drive, (419) 394-1294.

Ken Drenten is creator and editor of Dusty-Tires.com, a travel blog for out-of-the-ordinary places in Ohio.

Subscribe to Dusty Tires and receive a weekly email with the latest blog article. It’s free!

All rights reserved, Dusty Tires (dusty-tires.com), 2025.