I finally used my 75 ranger to find a sea snake near Redfeather Island. I think there's only 1 in the Buried Sea that keeps respawning over and over, close to the surface not on the bottom.
I searched all over deadbone reef area and no luck. Brought out my ranger to track them and found them right by the main island, north end. Some static, some roaming. Also found quite a few near the Katta Whirlpool Island.
These have shown up for me quite a ways off shore of Deadbone Reef. Seemed kind of far away to be specific to that island, took a while to fine em. Normal mobs, don't summon or cast that I have seen. With them under water, I just root + rot them, so I can't say how hard they hit. Not hard at all.