Why the duck have waterproof feathers?

ducks have waterproof feathers so that the water rolls off and isn't absorbed, it would make them heavier and more difficult to swim if they didn't have waterprrof feathers, it also keeps their feathers dry for warmth. imagine yourself swimming in your clothes as opposed to in a wetsuit or bathing suit? the waterproof feathers are like a wetsuit or beathing suit for a duck