Twelve black-and-white Magellanic penguins have been returned to the chilly seas off the Atlantic coast of Argentina after they were rescued and rehabilitated from health issues including malnutrition and anemia.

The boot-high penguins waddled down a windswept sandy beach after being released by conservationists, paused for photos with onlookers before taking the plunge back into the sea and swimming off to freedom.

"We found these animals in a state of malnutrition and dehydration," biologist Sergio Rodriguez, in charge of the rescue center at the Mundo Marino Foundation, said on the beach near the town of San Clemente del Tuyu.

The lack of plumage, he explained, forced the penguins to retreat to the beach because they could not maintain their temperature in the sea.

There are some 2.2 million to 3.2 million adult Magellanic penguins, named after Portuguese explorer Ferdinand Magellan. They are mostly found around Argentina and Chile, according to the International Union for the Conservation of Nature and Natural Resources.