Used to come across them all the time in late Spring and early Fall, when trail running in the Bay Area near Crystal Springs Reservoir. One day I spotted five on or near the trail. Babies. I was getting sick to my stomach, lol. Another time I almost stepped on one coming through a rocky section - suddenly my stride lengthened by a couple of feet as the adrenaline hit, haha. But never really any danger, nor have I even seen one coiled up except as a kid. Only have seen a couple while on the mountain bike, and those were in the Sacramento foothills.

Here in the Philippines there are poisonous sea snakes, mountain vipers and pythons, I've only seen the last and they don't bite. If you do get bit by a viper though, you're dead because they don't stock anti venom in the hospitals and a viper bite here will generally kill you in 30-45 min. Of course they're rare. In Australia I've heard there's a snake that is very aggressive and will *chase* you.