Their wings have been turned into flippers for swimming in the sea and
tobogganing on snow. The penguins come back over hundreds of miles of
trackless waste to their birthplace, where they breed. When they reach
the Antarctic shore they walk with determination to a suitable site,
often at the top of a steep cliff. Some species waddle 130 steps per
minute, 6 inches per step, two-thirds of a mile per hour.]