The best time for Christmas island is depending on the moon calendar. In last phase of the moon shrinking in winter the red crab migration is taking place. You can spot millions of crabs moving around the island.
Christmas Island is a small nature paradise in the indian ocean. It is called the galapagos of Australia. The main species on the island are million of crabs; either the red ones, blue ones or even the large robber crabs. Almost 80% of the island are nature reserves. In the forest many birds are nesting; red foot boobies or even teh endemic abbott boobies. There are several hiking trails in the forest. The island has serveral beaches which are difficult to access due to the topography of the island.
Around Christmas Island are many dive spots whre you can spot from small endimic species up to big whale sharks.
Additional information can be found on the web site of the Christmas Island Tourism Association: