Most of the park's area forms the headwaters of the Athabasca River, which originates in the parks extreme southernmost point at an unnamed lake unofficially known as Columbia Lake due to it being fed by one of the Columbia Icefield's many outlet glaciers. Despite its misleading name, the well-known Athabasca Glacier is actually the source of the Sunwapta River, a tributary of the Athabasca, not the main river itself. Other major tributaries of the Athabasca River that drain large areas of the park include the Maligne River, the Snake Indian River, Rocky River and the Miette River. The northernmost area of the park is drained separately by the Smoky River. Both the Smoky and Athabasca Rivers form part of the Mackenzie River drainage, the largest river system in Canada, which itself is part of the Arctic Ocean basin. The southeast section of the park is drained by the Brazeau River which is part of the Saskatchewan/Nelson River system which ultimately flows into Hudson Bay.
