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 ...
Sea snakes are very poisonous, but fortunately not aggressive. I read a news article in recent months that they were showing up further north on the Pacific West’s shores due to changes in the Pacific Ocean’s warm current: