Researchers discovered that the eyes of sharks, including bull and tiger sharks, are not designed to distinguish different colours and so they see the world in black and white.
That means against the light blue of the sea, it would be better to wear light coloured swimwear in order to reduce the contrast with the water.
The study backs up statistics from the International Shark Attack File (ISAF) which shows that the vast majority of attacks happen to divers and surfers wearing black wetsuits.
The team at the University of Western Australia and the University of Queensland examined the eyes of 17 species of shark including bull sharks, tiger sharks, reef sharks and Port Jackson sharks.
They found that their retinas had only one kind of cone – or light detector – that was only able to detect light or dark. That means a red apple would be just a dark shade to them.
Humans, in contrast, have three cones to distinguish colour, red, green and blue.
Professor Nathan Hart, the lead author, said a shark's vision could be compared to watching black and white television.
"If they lack colour vision, it means that brightness contrast is more important for detecting and identifying objects," he said.
via Sharks are colourblind new research finds - Telegraph.