Grand Lake St. Marys Seaplane Base

Grand Lake St. Marys Seaplane Base is a public use seaplane base located five nautical miles (9 km) southwest of the central business district of St. Marys, a city in Auglaize County, Ohio, United States. It is owned by the Ohio Division of Parks & Recreation and is located on Grand Lake St. Marys, a lake and state park in Ohio. The airport is a significant meeting place for the Ohio Seaplane Pilots Association.

Facilities and aircraft
Grand Lake St. Marys Seaplane Base covers an area of 643 acre at an elevation of 871 feet (265 m) above mean sea level. It has one seaplane landing area designated 9/27 and measuring 7,000 x 4,000 ft (2,134 x 1,219 m). For the 12-month period ending September 27, 2022, the airport has 12 aircraft operations per year, all general aviation.

The airport does not have a fixed-base operator, though avgas is available.