Natural World: Whale Shark

Beginning at the fabulous coral reef of Ningaloo in Western Australia, intrepid marine biologist Mark Meakin attempts to unravel the mysterious wanderings of the biggest fish in the sea. Whale sharks grow to more than 12 metres long but are gentle, filter-feeding giants; even Mark's five-year-old son can swim alongside them. Yet no-one knows where they go once they leave Ningaloo's turquoise lagoons.