If it's around your neck, and you really do mean putting the snake completely underwater, I picture you either bending over a tub of water and submersing your head to your shoulders or you standing in neck deep water with just your heat not submerged, hoping the snake will not, in both instances, periscope itself a breath or three.
This may need secondary consideration prior to actual implementation.
If you just yank long enough and hard enough, eventually they'll come loose.
Really though, depending on the snake, both species and individual, starting at one end and unwrapping to the other end is what I do. Usually I start with the tail, but not always.