Formation of the cavern began about 25 million years ago. It now soars to the height of a 12- story building and stretches the length of a football field. Care is taken not to disturb the natural habitat of the wild animals that dwell here. Sea lions gather in this natural amphitheater, usually during fall and winter. In spring and summer, they breed and have their young on rock ledges just outside the cave. The caves are also a major nesting ground for several species of birds, including Pigeon Guillemot, Brandt's Cormorant, and Western Gull.
