Christmas Island belongs to its crabs. Each year, when the first rains of the wet season soak this remote Indian Ocean outpost, tens of millions of scarlet red crabs stream out of the rainforest and march to the sea to breed — one of the largest animal migrations anywhere on land. The timing is set by the moon: the crabs must reach the coast and release their eggs before dawn on a receding tide in the last quarter, so rangers close roads, lay one-way barriers and build crab bridges to keep the red river moving. The island itself is a limestone plateau that rises steeply from deep ocean south of Java, and about two-thirds of it is protected as Christmas Island National Park — a jungle-covered tableland of rainforest, sea cliffs and limestone caves. Sharing that forest is the robber crab, the world's largest land invertebrate, a metre across and heavy enough to crack a coconut; Christmas Island holds the biggest population left anywhere.
Away from the migration, the island rewards slow days. You can swim in The Grotto, a sunlit pool inside a sea cave, watch swell explode through coastal blowholes, or follow boardwalks through the Dales to the mossy cascade of Hugh's Dale waterfall. Overhead wheels the golden bosun, an apricot-tinged tropicbird found nowhere else and adopted as the island's emblem. Only about 1,700 people live here, most of them in Flying Fish Cove, the small settlement founded in 1888 when the island was opened for phosphate mining. Time a visit between October and December and you may catch the crabs on the move; come in the wet season and whale sharks gather offshore, drawn by the billions of crab larvae washed into the sea after spawning.