Sea Serpent is one of many snake genres, which can be a sticking point for many solvers. (It's me, I'm many solvers.) I don't actually know too much about the history of this type; I was able to find it in a 2003 24HPC round but am not sure if this is actually where the genre originates. There are definitely aspects of this type which can be annoying, but overall I think it's friendlier than normal Snake. Sea Serpent doesn't have a "no diagonal adjacency" rule, and it's possible to place clues which behave more locally.
Rules: Shade some cells to form a non-intersecting path which does not touch itself orthogonally. Circles mark the ends of the path. Clues cannot be shaded, and represent the total number of shaded cells that appear in the indicated directions.
(Example taken from WPC 2011. Here the snake is represented by a path rather than by a group of shaded cells.)