Round Lake State Park, State park in Bonner County, US.

Round Lake State Park is a 142-acre public recreation area in Bonner County, Idaho, surrounding 55-acre Round Lake. The lake occupies a basin formed by glacial activity during the Pleistocene. The park provides campsites, trails for hiking, biking and skiing, and access for swimming, fishing and non-motorized or electric boating.

Round Lake was carved out by glacial activity during the Pleistocene epoch, long before the land became a park. The state park now covers 142 acres around the 55-acre lake, four miles southwest of Sagle in Bonner County. The sources give no founding date for the park itself.

The park's name comes from the 55-acre lake at its centre, and the surrounding woods shelter black bear, moose, grizzly bear, beaver, deer and waterfowl. Birdwatchers and wildlife observers come for these species, and the lake's restriction to non-motorized and electric craft keeps the setting free of engine noise.

The park lies four miles southwest of Sagle, about 14 km south of Sandpoint, at roughly 648 m elevation, with surrounding ridges rising to about 947 m. Trails serve hiking, biking and skiing, and the lake is open to non-motorized and electric-powered watercraft only. Bring insect repellent for the forest and shoreline.

Only non-motorized and electric boats are allowed on the water, keeping the lake quiet and free from engine noise. This rule makes the lake uncommon as a place where you can enjoy boating without the usual motor sounds.