Lake Opinicon is bordered by QUBS Point, Sugarbush Island, the Bonwill Tract and the Cape-Sauriol Environmental Studies Area (Concession 14, Lots 15-16; Concession 15, Lots 16-20; Concession 16, Lots 1-2, Concession 17, Lots 1-3; Concession 18, Lots 1-2 of South Frontenac Township, Frontenac County and Concession 7, Lots 13-16; Concession 8, Lots 12-17; Concession 9, Lots 13-16; Concession 10, Lots 14-16 of Rideau Lakes Township, Leeds and Grenville County). Mean depth = 2.8 m; maximum depth = 11.3 m; surface area = 788.0 ha, shoreline = 61657.5 m. Lake Opinicon is part of the Rideau Canal. To the north is Indian Lake, to the south is Sand Lake, both of which are sources of inflow and outflow. Lake Opinicon also receives inflow from a series of small creeks and two major creeks: Hart Lake Creek and Rock Lake Creek.