You see a sea serpent.
Notes
Part of the Journey mission of A Pirate's Tail Quest.
Abilities
Splash Wave (1500-2500; deals Physical Damage)Damage Taken From Elements
Physical 
Death 
Holy 
Ice
Fire
Energy
Earth
Drown
Location
Around the raft near Rascacoon.
Behaviour
It only moves in a straight line from west to east and thorw its wave towards the raft at each step. A sea serpent never retreats.
Strategy
Watch its movement and avoid its wave.