I have come face to face with a great white whilst snorkeling. Thankfully it was probably better described as a not so great white, approx 4-5 foot but underwater through googles whilst coming around some rocks and surprising the proverbial out of me, it was at least 30 feet long with teeth 12" long.
Have also been out surfing at dusk just near a wharf where they had caught 400 sharks over 4 weeks and watched one of the barrels they used as a bait float get dragged back and forth. Never paddled so fast in my life.