The Channel Islands, Monterey Bay, Gulf of the Farallones and Cordell Bank National Marine Sanctuaries cover more than 9,500 square miles of ocean habitat. While most fishing and shipping are still allowed within sanctuary waters, some activities are now regulated or prohibited. Patrolling such an immense area by boat would take days... but now sanctuary managers are taking to the air in a rugged de Havilland DHC-6 Twin Otter bush plane to get a bird's eye view.