Ask Nature
(1)Plumage releases air to propel body out of water: emperor penguin
http://www.asknature.org/strategy/5efd91776f9afa44b0fe26900c66356c

(2)Feathers trap air to provide warmth: emperor penguin
http://www.asknature.org/strategy/002043266864ae525a43a4a27f767999