Beaver Fur -

: Beavers use an oily secretion called castoreum from their scent glands to groom and waterproof their coats, allowing them to stay dry even while submerged for up to 15 minutes.

Beaver fur is a highly specialized biological material known for its unique dual-layered structure, which provides both extreme insulation and waterproofing. Historically, it was the primary driver of North American exploration and trade, fueling a global industry centered on high-status fashion, particularly felt hats. Today, while no longer the dominant global commodity it once was, beaver fur remains a subject of scientific interest as an environmental bioindicator and a managed resource in wildlife conservation. beaver fur

: It consists of long, coarse, glossy "guard hairs" that repel water and a dense, short, fine underfur for warmth. : Beavers use an oily secretion called castoreum