I've seen what appears to be two sea snakes washed up on the beach - in Teacapan a few years ago and again a few days ago in Mazatlan. From what I can tell online these are way out of their customary ...
Don't forget about the similarities of eels and snakes. On board a shrimper when the crew hauls in either the chango monkey or main net they give a wide berth to the contents. There are stories, true or not, of crewmen being bitten by a snake and not making it through the night.