Rideau District is geographically large; 178 statute miles (287 km) from Deep River in the northwest to Cornwall in the southeast and 104 miles (168 km) from Kingston in the southwest to Ottawa in the northeast.
The elevations of boating waters in the District range from highs of about 429 ft (130.9m) above sea level on the Tay Canal at Perth and 500 ft (152.5m) on the Holden Lake section of the Ottawa River. The lows are 152 ft (46.5m) on the St. Lawrence River below Cornwall and 137 ft (41.8m) on the Ottawa River above Carillon Dam. Lake Ontario is at 243 ft (74.1m).
The neighbouring CPS Districts are Quinte District to the southwest, Voyageur District to the northwest and Amiral and St Lawrence Districts to the east. District 6 of United States Power Squadrons lies to the south.