Quetico is near the southern edge of the Canadian Shield, an exposed 1000-mile expanse of ancient Precambrian rock, some of which is among the oldest exposed rock in the world.
The park contains numerous "young" lakes (only tens of thousands of years old) that are held by this ancient bedrock.
Due to its proximity to the Laurentian Divide, the park can be considered to be in the headwaters of the Hudson Bay watershed.
It and the adjacent Boundary Waters Canoe Area Wilderness in the United States comprise the most popular canoeing area in the world.

The southern part of the park is drained by the Basswood River, the central and eastern parts of the park by the Maligne River, and the northern part of the park by the Quetico River.
 All of these rivers flow into the Namakan River west of the park.
It flows into the Rainy River, Winnipeg River, Nelson River and finally into Hudson Bay.
Quetico is near the southern edge of the Canadian Shield, an exposed 1000-mile expanse of ancient Precambrian rock, some of which is among the oldest exposed rock in the world. The park contains numerous "young" lakes (only tens of thousands of years old) that are held by this ancient bedrock. Due to its proximity to the Laurentian Divide, the park can be considered to be in the headwaters of the Hudson Bay watershed. It and the adjacent Boundary Waters Canoe Area Wilderness in the United States comprise the most popular canoeing area in the world.
The southern part of the park is drained by the Basswood River, the central and eastern parts of the park by the Maligne River, and the northern part of the park by the Quetico River.  All of these rivers flow into the Namakan River west of the park. It flows into the Rainy River, Winnipeg River, Nelson River and finally into Hudson Bay.
Quetico Provincial Park