In this astonishing natural oasis, classified as a world biosphere reserve by UNESCO and admitted to the club of the "most beautiful bays in the world", the traditional canoes which criss-cross the mazes of bolongs (narrow waterways winding through the mangroves) lead discovering thousands of islands and islets that serve as refuge for nearly 150 species of rare and endangered birds, including the largest nesting colony of royal terns in the world.