Whale sharks can be identified by a tool originally developed by NASA to chart the night sky. But instead of mapping stars, the algorithm analyses the pattern of spots on their flanks and topsides and compares them to other sharks in a database. Getting into the water with one, then, could be likened to taking a dip with a living galaxy. And while that might be stretching things a little, with its gaping mouth, strangely flattened head, the ridges along its side and the dense pattern of spots set against an inky-black background, a whale shark could legitimately be described as being out of this world.

At up to 12m long it is the largest fish on Earth. Of course, there is nothing to fear from these sharks, because despite their size they eat nothing much larger than a shrimp. The best time to head to Ningaloo Bay is between mid-March and mid-September. While sightings can never be guaranteed, some operators claim a success rate of greater than 98 per cent, and offer you another go if you’re one of the unlucky few who misses out. It’s got to be worth a try.