What do you do when you’re on the bottom rung of a boat ladder, still half in the water, and a metre-wide mouth is heading towards you – attached to a midnight-blue body some six metres long?

I asked myself this as I stood captivated by the sight of a member of the biggest fish species on Earth cruising towards me. When he was just centimetres away, he calmly ducked, and a few seconds later his massive form disappeared beneath the boat.

This was Chompy, a whale shark who has been visiting Ningaloo Reef, off Western Australia’s Coral Coast, for eight years. He is well known by the local diving operators because a large part of his dorsal fin has been 'chomped' away, possibly by a more aggressive shark species.

Whale sharks are indeed sharks, and can grow to a whopping 20 metres. Between April and July, Ningaloo Marine Park is one of the few places where these normally solitary leviathans congregate. Tourists are waking up to this. Exmouth is the only town in the area and last year was its biggest-ever season, with 14,000 visitors.

Planes head out to spot the sharks, before motor cruisers drop divers in the water beside the sharks' straight feeding paths. Human-curious whale sharks like Chompy will stick around a boat, and he circled us for a magical hour. It was as if he wanted to come and visit our world. Little is known about these creatures – perhaps he was as curious about us as we were about him.

What to see on Ningaloo Reef:

  • Between May and November, manta rays come to the reef and can be seen by divers and snorkellers.
  • From July to November the migration of humpback whales passes by. They can be viewed from land or on boat-based whale watching trips.
  • November to February is turtle-nesting season, when three species of sea turtles lay their eggs on the shores of the Coral Coast.

Dale Templar was the Series Producer of BBC One’s Human Planet, and is now in search of her next wildlife encounter.