It's a natural phenomena worthy of an Attenborough voice over -- up to 50 million bright red crabs making an annual pilgrimage from the forest to the beach at Christmas Island.
That's probably why Sir David Attenborough has visited Christmas Island, along with every wildlife photographer worth their salt.
Early Friday morning, the beaches of Christmas Island were blanketed with female crabs delivering their precious clutch of eggs into the waiting shoreline.
Parks Australia was there with a live stream of the action.
Before the female crabs, there's an initial migration of male crabs across the island who reach the beach, fraternise with the female crabs and then go dig burrows designed for a bit of privacy.
A bit more than a week later, the females are ready to disperse their eggs into the ocean.
Christmas Island is between Indonesia and Western Australia.