Why do penguins waddle when they walk?

Penguins waddle because of their unique body structure and adaptations for swimming rather than walking. Their short legs and webbed feet are positioned far back on their bodies to maximise efficiency in water. While walking on land, this alignment creates a side-to-side motion, or waddle, to maintain balance. The waddling gait also conserves energy, as their stiff, upright posture minimises muscle use. Despite their awkwardness on land, penguins are agile swimmers, capable of reaching speeds of up to 15 mph in the water.