Grindstone Falls is a stretch of rapids on Penobscot River in Penobscot County, Maine, in the Acadian Plains and Hills region. It lies about 6.8 miles north of East Millinocket as the crow flies.
The Acadian Plains and Hills of Maine are rolling, glaciated forest of spruce, fir and northern hardwoods with countless lakes, bogs and rivers. Rivers drop over granite and slate ledges in falls and rips. Penobscot River carries 2 recorded rapids along its course.
There are 20 recorded rapids in Penobscot County. Meadow Brook Rapids, is about 1.7 miles away. Crowfoot Rapids, is about 2 miles away. Big Eddy, is about 5.3 miles away.
Grindstone Falls is located at 45.7248° N, 68.5885° W. The listing is based on the World Waterfall Database, one of the sources compiled by the U.S. Geological Survey in its inventory of waterfalls and rapids of the conterminous United States. The position was verified on aerial imagery. Details on trails, parking and access have not been documented for this rapid yet.