The adventurous actor was on a dive in Hawaii this year, when he encountered the predator, that apparently came ‘out of nowhere.’
Speaking to TV host Jimmy Fallon, Zac said: ‘I was out there for maybe about 45 minutes, and all of a sudden, out of nowhere, all of the Galapagos sharks - which are like the 7 - 10 foot sharks - just dive.’
As it turns out, the sharks had disappeared because a larger, more powerful predator was among them.
‘I turned left and I see about a 14 foot tiger shark…swimming towards me.’
Efron, who is something of an adrenaline junkie, said he managed to slow his heart rate and stay as calm as he possibly could.
‘I geld my breath, I crossed my arms and I let the shark know that I wasn’t prey. I just sort of stared into its eyes - I’m not joking.’
But then, as the predator began to swim away, Efron saw his chance to hitch a ride.
‘I don't know what happened, but I guess I really like to charge life, so I just grabbed onto its fin and rode it all the way back to the boat.’