Behave like a duck, stay calm on the surface but paddle like crazy underneath.

The earliest located English-language instance (1934) appears in U.S. columnist Raymond Clapper’s discussion of political and business maneuvering around President Franklin D. Roosevelt. Clapper presents the image as something “the Japanese call ‘duck diplomacy’,” describing a calm surface appearance paired with intense hidden effort. Later uses apply the same idea to politicians, institutions, acting, and service work, sometimes swapping “duck” for “swan” and varying the intensifier (e.g., devil/dickens/hell/crazy).

The saying advises maintaining a composed outward demeanor while working strenuously behind the scenes. It highlights the contrast between visible calm and the unseen labor required to sustain it, often as guidance for professionalism under pressure.

Float along placidly on the surface, but underneath you are paddling like the dickens with your feet.

Keep calm and unruffled on the surface but paddle like the devil underneath.

Calm on the surface, but paddling like hell underneath.

Like a swan gliding on the lake; underneath, they’re paddling like crazy.