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 ...
We get yellow bellied sea snakes on a semi-regular basis in Zihuatanejo and occasionally on our Southern California beach. They are the most widely distributed snake in the world, but I read somewhere that they were unable to bite when they were out of the water-probably because they are in dire straights when they are on shore! They are beautiful.