Watch as the penguins march to their new home at the Detroit Zoo’s Polk Penguin Conservation Center. Opening April 18, the 33,000-square-foot penguin center is the largest facility for penguins in the world and features a 326,000-gallon, 25-foot-deep aquatic area where visitors can watch more than 80 penguins of four species explore their habitat. An underwater gallery and two acrylic underwater tunnels