Red Crabs Swarm Island by the Millions: Cost $1,500 to Watch (VIDEO)

Red crabs swarm Christmas Island every year as part of the migration process. This year, the event has been slated as one of the top ten "most spectacular migrations."

Visitors who visit Christmas Island in Australia anywhere from November to January may be lucky enough to witness the red crab migration. The timing of the migration depends on the weather, as the crabs will only move when it is raining. This year the crabs were slated to begin their migration in January.

The event involves a trek made by millions of crabs that leave their burrow homes in search of the sea. The male crab usually begins the migration cycle, they are the first to arrive at sea although they are quickly joined and then outnumbered by female crabs according to

The females stay behind to produce eggs after mating with male crabs. Male crabs will take 1 to 2 days to make it to sea. When the female crabs arrive, it takes 5 to 6 nights for them to release their eggs into the sea.

"They descend cliffs, climb banks and maneuver around obstacles to reach the shoreline and lay their eggs, eventually returning to the island's central plateau with their offspring in tow," a CNN report described, listing the event as "One of the Most Spectacular Migrations" in a recent March report.

Expeditions to witness the migration can cost upwards of $1,500.

Other migrations that made the list include the migration of Bald Eagles in the British Columbia of Canada and the march of penguins in Antarctica as witnessed in the 2005 documentary "March of the Penguins."

A nine day expedition is offered to witness the penguin migration, but the cost is upwards of $40,000 a person. Flamingos in Kenya and Whale Sharks in Mexico were also noted.