Petawawa is a town located in the eastern portion of Southern Ontario. Situated in the Ottawa Valley, with a population of 18,160, Petawawa is the most populous municipality in Renfrew County.

The Ottawa Valley is the valley of the Ottawa River, along the boundary between Eastern Ontario and the Outaouais, Quebec, Canada. The valley is the transition between the Saint Lawrence Lowlands and the Canadian Shield. Because of the surrounding shield, the valley is narrow at its western end and then becomes increasingly wide as it progresses eastward. The underlying geophysical structure is the Ottawa-Bonnechere Graben. Approximately 1.3 million people reside in the valley, around 80% of whom reside in Ottawa. The total area of the Ottawa Valley is 2.4 million ha. The National Capital Region area has just over 1.4 million inhabitants in both provinces.