Bright red crabs like this one number in the tens of millions here on Christmas Island, a territory of Australia located in the Indian Ocean. It’s warm on the island this time of year, and these crabs are migrating to the sea, where they will mate and spawn. The event is quite a spectacle—onlookers will see rivers of crabs, thousands of them at a time climbing over fences and crossing roads on their journey, which attracts tourists to the remote destination. This isle itself was named by an English sea captain who discovered the destination on Christmas Day of 1643.