No matter how many times you tell your rational brain that a shark doesn't really pose all that much of a risk, there's no stopping your limbic system from reacting. I'm surprised you can't hear the sound of my heart pounding against my ribcage in this video. The shark is a gray reef shark. And he was probably about 5' or 6' feet long.
Ok, now that I've shown you all the nice guys I met - it's time to see the SCARY GUYS! The first scary guy wasn't all THAT scary because he was sleeping! Sleeping shark! (Nurse shark, I think).