Christmas Island

Christmas Island lies in the Indian Ocean, closer to Java than to the Australian mainland, a limestone plateau of rainforest fringed by cliffs that drop into very deep water. Two thirds is national park. Its most extraordinary event is the red crab migration: at the start of the wet season, cued by rainfall and the moon, tens of millions of red crabs leave the forest and move to the sea to breed, covering roads, cliffs and gardens, with roads closed and crab bridges built over them. The island also holds robber crabs, the world's largest land invertebrate, seabird colonies including the endemic Abbott's booby, and dive walls dropping into blue water.

What you actually see

• The red crab migration - tens of millions of crabs crossing the island in the wet.
• The robber crabs - the world's largest land invertebrate, present year-round.
• The seabird colonies - frigatebirds, tropicbirds and the endemic Abbott's booby.
• The dive walls - reef dropping into deep ocean directly offshore.

When to go

October to December for the crab migration, whose timing shifts each year with rainfall and the moon and is announced only shortly ahead. Diving is best from December to April. Flights are infrequent and should be booked with flexibility.

Honest expectations

The migration timing cannot be predicted far ahead and travellers regularly miss it. Flights are limited, expensive and subject to disruption. Accommodation is scarce. The island has an immigration detention facility, which some visitors find an uncomfortable presence.

Nearby

The Cocos Islands lie southwest; Perth is the mainland link.