In depths of 7 to 20 metres, simple snorkels will let you admire the multicoloured coral and starfish of all sizes. You'll come across rays, sea turtles (that lay on the island), lots of tropical fish and perhaps nurse sharks.
For those who prefer walking, a stroll on the white sand of Nosy Tanikely beach will lead you to the enormous rock where the tropicbirds nest. At the end of the Island a lighthouse dating from the early 20th century gives you an amazing view of the ocean and Nosy Be.
Colonies of fruit bats live on the Ile de la Petite Terre (Nosy Tanikely) and if you're lucky you may see an osprey (or anjoay), an endangered native species.