It's a weird setup. Harpoons were introduced as a mechanism for serpent hunting, but the harpoons were absurdly strong to make that possible which launched the Youtube Viking Space Program (which was great fun and did the game absolutely no harm at all) so the harpoons were toned down to realistic physics settings and now they're near-useless at the mythical beast hunting role they were introduced for.

Should just make serpents super crazy aggressive so if you shoot them one time they'll follow you onto land and try to drag you out to sea. Also now I wanna see a troll / serpent / abomination wrestlemania rumble.