What essential function does the coat's density provide for a Boykin Spaniel bred to work in water and marshlands?

Answer

A necessary degree of insulation and water resistance

The density of the coat is important because it provides the necessary degree of insulation and water resistance for a dog working in wet environments.

What essential function does the coat's density provide for a Boykin Spaniel bred to work in water and marshlands?
DogbreedhairFurBoykin Spaniel