Chinstrap penguins primarily eat krill, or Euphasia superba, small crustaceans that live in the ocean. The diet of a chinstrap penguin might also include other crustaceans and small shoaling fish, but these do not contribute significantly to the penguin's total caloric intake.
Chinstrap penguins mostly obtain food close to shore, so their diets are limited to sea creatures found along the shoreline of Antarctica, the South Sandwich Islands and other small islands in the Antarctic Ocean where they live.
To obtain food, a chinstrap penguin typically dives into the water just offshore, where it quickly captures and eats its prey without leaving the water. Dives generally last less than one minute, and chinstrap penguins usually limit dives to less than 200 feet below the surface. A single chinstrap penguin makes multiple dives into the same patch of prey during a given feeding.
Chinstrap penguins hunt and eat both during daylight hours and throughout the night. Both the frequency of dives and depth of dives are greatest during the midday hours when the sunlight penetrates more deeply into the ocean and krill are more visible. Unlike most penguin species, chinstrap penguins can feed even in extremely low-light conditions with light levels as low as 1 lux. During the breeding season, each member of a mated pair of chinstrap penguins takes turns feeding and incubating the egg throughout the day and night.