Sea Snakes

When we visited Cozumel back in the early 2000's, we were snorkelling near where there was a sunken plane if I recall correctly. It was beautiful, and we used to take the sealed packets of crackers with us to crumble and release for the fish (parrot, sergeant majors, etc) to swim around us for photos. All of a sudden as we were headed out quite way from the beach snorkelling I looked up and hubby pointed to look down and there was what appeared to be a snake for sure and it was black and white zig zag type pattern. I've never swam/finned back to shore as fast in all my life LOL.

PS: A little off track but interesting to us. We've seen other types of very long fat snakes swimming across Lake Shasta as well!