Nothing like going for a little underwater expedition and having a massive great white casually swim past below you. Luckily for this guy the shark had probably already eaten.

Grayson Shepard uploaded the footage to YouTube alongside this explanation:

It approached from behind and had already passed me when I saw it. Turning and running could trigger the predator/prey instinct, so I stood my ground aiming my speargun at its head. Fortunately, for whatever reason, this one turned at about 15′ away and gave me a full profile view. I watched until it disappeared again then decided to take my chances with decompression sickness rather than a third visit from the shark, so I skipped the remaining 2 minutes of wait time and headed to the surface and safety of the boat.

It’s like your worst nightmare. I felt totally helpless. It was like it saw me before I saw it. That spooked me.

Terrifying, though I’m sure Grayson would have properly crapped himself if the shark looked anything like its deep sea cousins.