Here is a quote from the quick thinking surfer:

“I instantly just jumped away. It kept coming at my board and I was kicking and screaming. I just saw fins. I was waiting for the teeth.”

Here is a bit more from wikipedia on unprovoked attacks:

Large sharks species are apex predators in their environment,^[37] and thus have little fear of any creature (other thanorca^[38]) they cross paths with. Like most sophisticated hunters, they are curious when they encounter something unusual in their territories. Lacking any limbs with sensitive digits such as hands or feet, the only way they can explore an object or organism is to bite it; these bites are known as exploratory bites.^[39] Generally, shark bites are exploratory, and the animal will swim away after one bite.^[39] For example, exploratory bites on surfers are thought to be caused by the shark mistaking the surfer for the shape of prey.^[40] Nonetheless, a single bite can grievously injure a human if the animal involved is a powerful predator like a great white or tiger shark.^[41]

We do share the water with many creatures and we’re glad this brave and clever athlete made it back!

thanks to euronews.com for the great info