I WONDER - How Did Vikings Make Their Clothes Waterproof?

Vikings lived in harsh, cold, and wet environments, necessitating clothing that kept them warm and dry. Their clothing was made from wool and fur for insulation. To protect against rain, Vikings innovatively waterproofed their clothing using treated skins with beeswax and fish oil. Leather was also used as a waterproof material.

Why was it important for Viking clothing to be waterproof?

What types of materials besides wool and fur did Vikings use for waterproofing?