I want to know the answer to the following question:
For what  did Canadian natives use asphalt as a waterproofing material?
All the background I'm provided with is that "Canada has the world's largest deposit of natural bitumen in the Athabasca oil sands and Canadian First Nations along the Athabasca River had long used it to waterproof their canoes.". Is that enough to answer the question?
Answer: yes