Which penguin species is the fastest swimmer, reaching about 36 kilometres per hour?

The gentoo penguin is generally recognized as the fastest swimming penguin, reaching about 36 kilometres per hour.

Gentoos use powerful flipper strokes and streamlined bodies to accelerate through coastal waters. Their speed helps them pursue fish, squid, and crustaceans and may also help them avoid predators such as leopard seals. Exact speeds vary with conditions and measurement methods, so the figure is usually presented as an approximate maximum.

Gentoos are medium-to-large penguins identified by a broad white stripe above each eye that joins across the crown. They breed on the Antarctic Peninsula and on several sub-Antarctic islands, including the Falkland Islands and South Georgia.

The fastest-swimming claim is not the same as the deepest-diving claim. Emperor penguins are famous for exceptional dive depth, while gentoo penguins are especially associated with speed.