Field Notes Ohio

Ohio's parks, forests and wildlife areas with camping, the ancient mounds beside them, and the Buckeye Trail that links them. Stories, trails, wildlife, and where to eat and fuel up nearby. Book campsites on ReserveOhio.
Try:
The Buckeye TrailA 1,444-mile blue-blazed loop around Ohio, with all 26 sections.
›
Mounds & Earthworks43 ancient sites, including the Great Serpent Mound and the Newark Earthworks.
›
Historic Sites39 places, from Fort Steuben and Zoar to Camp Chase and the Rankin House, from the frontier to the Civil War.
›
Road Trips33 drives, from the Lincoln Highway to the Morgan Heritage Trail.
›
Lake Erie Beaches20 public beaches from Conneaut to Toledo and the islands, with a map.
›
Oddities & Roadside Attractions19 giants, ghosts and folk-art stops, plus a Mothman just over the line.
›
Caves & Caverns12 show caverns, recess caves and rock shelters, with a map.
›
Waterfalls34 falls from the Cuyahoga Valley to the Hocking Hills, with trail notes and a map.
›

Explore Ohio

One map for every park, mound, historic site, beach, cave, waterfall and oddity in the app.

Lake ErieWest Virginia27 places277 places77 places73 places35 places519 places1913 places1319 places1916 places168 places810 places1010 places109 places98 places820 places204 places43 places3Barkcamp State Park4 places47 places77 places76 places69 places917 places173 places3Harrison Lake State Park2 places2Forked Run State Park3 places32 places26 places610 places103 places32 places2

Tap a symbol for a preview, or search for a place. Open the key to show or hide categories.

117 parks in 7 regions

Grand Lake St. Marys State Park

Celina / St. Marys · Mercer & Auglaize Counties
Ohio Department of Natural Resources
13,500acres
—trail miles
1845established

Visiting information you can trust

Content last reviewed
September 2026 — this is when Field Notes Ohio's content was last checked, not a live status.
Primary official source
ODNR park finder (search this park)
Location confidence
Verified property location
Grand Lake St. Marys State Park, 834 Edgewater Dr, St. Marys
Check current conditions
Official conditions or closures
Reservations or tickets
ReserveOhio — camping and cabin bookings
Hunting or permits
Permitted in designated areas year-round with a valid Ohio license. Waterfowl hunting is the main draw given the lake's size and shallow margins.

Prices, hours, closures, campsite availability and trail conditions shown elsewhere on this page are not live — always confirm with the official source before you go.

The story of this land

In 1837 the state of Ohio decided to dig a lake. Not dam a valley — dig one, out of swampy prairie, to feed the Miami and Erie Canal and keep five feet of water in the channel. Roughly 1,700 German and Irish immigrants did the work with hand tools over eight years. The pay was about thirty-five cents a day and a jigger of whiskey, issued on the theory that it would fend off malaria and keep morale up. When they finished in 1845, the 13,500-acre Grand Lake was the largest man-made body of water in the world, connected to the canal by a three-mile feeder.

It is also enormous and shallow — averaging only five to seven feet deep — because that's what a canal reservoir needed to be. The St. Marys River nearby had already made this region strategically important as a link between the Great Lakes and the Ohio River, enough that the renegade Girty brothers ran a trading post here that grew into the town of St. Marys. 'Mad' Anthony Wayne passed through, and some of his men came back to settle.

The canal thrived about thirty years and then the railroads killed it. What saved the lake was oil. Strikes in the 1890s put derricks out on the water around 1891 — the first offshore oil drilling anywhere in the world happened on this Ohio canal reservoir. Over a hundred wells eventually operated. A pile of rocks near the center of the lake still marks the last producing one. By 1915 the state decided the canal was done and the lake should become a public pleasure resort, and in 1949 Grand Lake St. Marys and the other canal feeder lakes became the very first parks dedicated in Ohio's new state park system.

Things to do in the park

  • Boating across 13,500 acres — the largest inland lake in Ohio
  • Camping on the north shore with lake access
  • St. Marys Fish Hatchery on the eastern shore
  • Windsurfing and sailing — the lake's size and open fetch make it unusually good for wind sports
  • Find the rock pile marking the last producing offshore oil well

Trails

Maps, reviews and recent trail reports for Grand Lake St. Marys State Park.

Find trails on AllTrails →

Things to do nearby

  • Memorial Park in St. Marys, with a canal boat and memorial covered bridge
  • Miami and Erie Canal remnants throughout the area
  • Celina's lakefront and boardwalk
  • Wright State University's lake campus facility

Hiking trails

Limited formal trail mileage — this is a water-first park with facilities scattered around the shoreline. Short walking paths at the campground and day-use areas; the region's better hiking is inland.

Wildlife you might see

  • Three pairs of nesting American bald eagles
  • Heavy waterfowl use — this is a major migration stopover
  • Shorebirds along the extensive shallow margins
  • Surrounded by farmland; the original forest here was cleared by pioneer farmers

Fishing

  • Grand Lake St. Marys: saugeye, crappie, bluegill, largemouth bass, channel catfish, yellow perch. The St. Marys Fish Hatchery on the eastern shore raises saugeye and bass.
  • Note: the lake has had recurring harmful algal bloom advisories in recent years — check current ODNR and Ohio EPA status before swimming or keeping fish.

Hunting

Permitted in designated areas year-round with a valid Ohio license. Waterfowl hunting is the main draw given the lake's size and shallow margins.

Getting on the water

13,500 acres and only five to seven feet deep on average, which is the defining fact about this lake. Big open water with almost no depth: excellent for sailing and windsurfing, tricky for anything with a deep draft, and quick to churn up muddy in wind.

Launches & facilities

Multiple public ramps
Spread around the shoreline near Celina and St. Marys.
Swimming beaches
Several around the lake — check current water quality advisories before swimming.
St. Marys Fish Hatchery
On the eastern shore; raises saugeye and bass for state waters.

Good to know

  • Check Ohio EPA and ODNR advisories before swimming or keeping fish — harmful algal blooms have been a recurring issue here.
  • The shallow depth means wind builds a short, steep chop fast. Small boats should watch the forecast.
  • Sailing and windsurfing are genuinely good here, which is rare in Ohio.

The Lake Dug With Shovels and Whiskey

Grand Lake St. Marys was dug by hand. Starting in 1837, German and Irish immigrants, about 1,700 of them by one count, dug a reservoir out of a swampy prairie with shovels, axes and mule power to keep the Miami and Erie Canal full. They were paid about 35 cents a day and a jigger of whiskey, the whiskey being medicine against malaria. When it was finished in 1845 it covered 13,500 acres and was the largest man-made lake in the world.

The lake nearly did not survive. When the canal died, plenty of people, including one attorney general, thought the bottomland would be better as cornfields. A local faction convinced the legislature to keep it. Then oil was found in the late 1890s, and for a time the lake was dotted with derricks. A pile of rocks near the center of the lake marks the last producing well.

Behind the legend

The wages depend on who is telling it. ODNR and the tourism sites say 35 cents a day, and the local lake association says 30 cents. The lake association also says the lake was first 17,000 acres and shrank to 13,500, and says it was home to the world's first offshore oil well, a local boast that the lake is proud of. What is firm is that it took eight years, that the lake is only about 5 to 7 feet deep on average, and that it is still the largest inland lake in Ohio by area.

It also sits on a summit. Loramie Summit near New Bremen is the highest point on the canal, and water north of it flows north while water south of it flows south.

If you go

Find the rock pile near the center of the lake that marks the last oil well, or drive the shoreline and stop at the dam and spillway.

Historic sites near Grand Lake St. Marys State Park

Forts, villages, furnaces and lighthouses within reach of this park. Tap one for its story and visiting details.

Armstrong Air & Space Museum

Wapakoneta · Auglaize County · West-central Ohio
A domed museum in Neil Armstrong's hometown, home to the Gemini 8 spacecraft, his space suits and a moon rock.
Ohio History Connection
About 12 miles from this park · Opened 1972

Fort Recovery Museum and Monument

Fort Recovery · Mercer County · Western Ohio
The site of the worst defeat the U.S. Army ever suffered at Native hands, and of the fort built on its bones.
Site of two 1790s battles
About 25 miles from this park · 1791–1795

Lockington Locks

Lockington · Shelby County · Western Ohio
A group of stone canal locks in a small canal village, restored and open free from dawn to dusk.
National Register of Historic Places
About 30 miles from this park · 1833–1913

Johnston Farm and Indian Agency

Piqua · Miami County · Western Ohio
A restored farm, a museum of Ohio's Native peoples and a mule-drawn canal boat ride, all on the site of the old Piqua Indian agency.
Canal boat rides
About 35 miles from this park · 2,000 years; the 1811 agency to the canal era

Road trips through Grand Lake St. Marys State Park

Scenic byways and heritage drives that pass this park or run close to it.

Land of the Cross-Tipped Churches

West-central Ohio (Mercer and Auglaize counties)
A big lake with camping.
Scenic byway38.4 miles
Half a day · McCartyville to SR 29 west of Wabash

Miami and Erie Canal Scenic Byway

Western Ohio
Ohio's largest inland lake.
Scenic byway50 miles
Half a day · Miami County to Allen County

Neil Armstrong Scenic Byway

West-central Ohio (Wapakoneta)
Ohio's largest inland lake to the west.
Scenic bywayVaries
Half a day · Wapakoneta to Wapakoneta area

The Buckeye Trail at Grand Lake St. Marys State Park

Ohio's 1,444-mile blue-blazed loop passes through or beside this park. Tap a section for its route, camping, water and resupply.

19 St. Marys Section

48 miles · Miami, Shelby, Auglaize
Nearby camping options
3 parksTrail towns

Campsites

Electric site
Campground on the north shore with lake access
$35–39/night
Non-electric site
Basic sites
$25–29/night

On site

  • Showers and flush toilets
  • Multiple boat ramps around the shoreline
  • Swimming beaches
  • Dump station
  • Facilities scattered around the lake, intermingled with private property
Continue to ReserveOhio →
Field Notes Ohio isn't connected to ReserveOhio, so it can't hold a site or take payment. Tapping through opens it in a new tab — search "Grand Lake St. Marys State Park" there to finish reserving.
Prefer the phone?419-394-3611

Restaurants nearby

The Bay Restaurant
Lake-view breakfast and lunch, enormous portions. Closed Mondays, closes at 2 p.m.
Directions
Boardwalk Grill
On the Celina boardwalk with live music. Closed Mondays
Directions
Lakeside Hideout
Patio over the water on the south shore. Closed Mondays
Directions

Gas stations nearby

Marathon
24 hours in Celina
Directions
Sunoco
Well-run local stop, opens 5 a.m.
Directions

Details last checked 2026-09-22. Confirm hours and prices before you go.