Great Bear Lake is the largest freshwater lake that lies wholly in Canada. It is situated on the edge of the Canadian Shield, is transected by the Arctic Circle, and is bordered to the south by boreal forest and to the north by tundra. Water from Great Bear Lake drains into Canada's longest river, the Mackenzie. The northern shores of this lake have been inhabited for at least 6000 years by peoples whose livelihoods depended on the caribou.Great Bear Lake has been little impacted by development. In fact, scientists use it as a model of a young pristine lake. 

Its deep, clear, cold waters have very low productivity because nutrient levels are low. The main inhabitants of the lake are the four-horned sculpin, and various amphipods and copepods.

 

 Lake Nyasa is situated between Malawi, Mozambique, and Tanzania bordering all three. It is the second deepest lake in Africa and its tropical waters have more fish species than any other lake on Earth.