The third largest island in the world is Borneo, which is located in Southeast Asia and is divided among three countries: Indonesia, Malaysia, and Brunei. It is the world's third largest island, covering an area of 743, 330 square kilometers. Borneo is home to a wide variety of flora and fauna, including orangutans, elephants, and tigers. It is also known for its rainforests, which are some of the oldest and most biodiverse in the world.