The gentoo penguin is a species of penguin also known by the scientific name Pygoscelis papua. Two subspecies of the gentoo penguin exist: Pygoscelis papua papua, and Pygoscelis papua ellsworthii.

The gentoo penguin can be found on and around the Antarctic Peninsula and several Antarctic islands. In particular, it tends to inhabit plains on the coast, cliffs, and sheltered valleys, and prefers regions without much ice.

The third largest species of penguin, the gentoo penguin typically measures between 20 and 35 inches in height, with an average around 30 inches. The gentoo penguin's weight varies throughout its life; an average gentoo penguin can weigh up to 19 pounds for males and 18 pounds for females prior to molting, and may drop as low as 11 pounds for males who are about to mate and 10 pounds for females who are protecting their nests.

A defining characteristic of the gentoo penguin is the white stripe that crosses its otherwise black head; this feature as well as its orangey-red bill make the gentoo easy to recognize. The gentoo penguin also has white fronts and black backs and heads, as well as very pale pink feet. Its tail is relatively long, making it the most distinct of any species of penguin.

The average gentoo penguin's diet consists predominantly of crustaceans, which are supplemented with fish; a typical gentoo penguin's diet consists of only 15% fish. The gentoo penguin, however, is an opportunistic eater, and some gentoo penguins have been observed eating a diet of approximately equal amounts of crustaceans, fish, and squid due to availability.

The gentoo penguin is most comfortable in the water, and spends most of the year in the ocean. On an average day, an adult gentoo penguins spends the whole day hunting underwater, typically remaining close to the shore. The gentoo penguin can swim at speeds of up to 22 miles per hour underwater, and can descend as deep as 655 feet and remain underwater for as long as seven minutes at a time.

To breed, gentoo penguins venture to land in colonies. The gentoo penguin prefers areas free of ice in which to breed, and may breed either near the coast or quite far inland. Gentoo mating pairs, which often form long-lasting partnerships, construct circular nests from stones in which the female ultimately deposits two eggs. Both parents take turns incubating the eggs for a little over a month, after which chicks hatch.

After hatching, chicks remain in the nest for 30 days, during which time its parents take turns keeping the chick warm, or brooding, and searching for food. Chicks do not enter the ocean until they are about 80 to 100 days old. Before entering the water, chicks molt, developing juvenile plumage.

While the adult gentoo penguin has no natural predators on land, it is threatened by orcas, leopard seals, and sea lions in the water. Gentoo chicks and eggs are not as fortunate, being subject to attack by birds of prey such as the skua. Gentoo penguins also face a threat from humans, who may hunt them for their skin and oil.