Fee: No entrance fee. Fees apply for camping and shelter rental; reserve at reserveohio.com or (866) 644-6727.
About this park
Grand Lake St. Marys was originally dug by hand as a feeder reservoir for the Miami and Erie Canal, and it was the world's largest reservoir when it was built. The St. Marys River was a vital link between the Great Lakes and the Ohio River, so the region played an important role in opening the Northwest Territory. Today the park offers 52 miles of shoreline for boating and fishing, a family campground, a swimming pool and picnic areas. The off-peak camping season runs from November 1 to April 1, when electric service is available in the first loop, a dump station is available and a water hydrant is near the main office.
Grand Lake St. Marys State Park FAQ
Where is Grand Lake St. Marys State Park located?
Grand Lake St. Marys State Park is in St Marys, Ohio, at 834 Edgewater Drive. GPS coordinates: 40.5264, -84.5008. Get directions.
Is there an entrance fee at Grand Lake St. Marys State Park?
No entrance fee. Fees apply for camping and shelter rental; reserve at reserveohio.com or (866) 644-6727. Fees can change by season, so confirm with the park before you go.
How do I contact Grand Lake St. Marys State Park?
You can call (419) 394-3611. The park office can confirm RV site availability, hookups, length limits and current conditions.
Are there RV campgrounds near Grand Lake St. Marys State Park?
Yes. The closest RV-friendly campgrounds listed on ParkedRV are:
- Oak Hill - Lake Vesuvius (165.1 mi, reservable)
- Iron Ridge - Lake Vesuvius (166.1 mi, reservable)
- Boat Gunnel Group Campground (176.0 mi, reservable)
How current is this information about Grand Lake St. Marys State Park?
This listing was last updated on October 6, 2026. If something is out of date, let us know and we'll fix it.