Whale sharks can grow up to the size of a bus and they journey to Mexico every year to feast on the tiny fish eggs that are plentiful here at this time of the year. Whale shark frequent the area around Cancun and boat tours run from May 17th to September 17th. I went with a company called Mexico Whale Shark. They run daily trips leaving from the Cancun area and offer pick up from your hotel. The tours leave early at 6 am!