A water elemental is a cresting wave that rolls across the ground, becoming nearly invisible at it courses through a larger body of water. It engulfs creatures that stand against it, filling their mouths and lungs as easily as it smothers flame.
Water Elemental
Primal Spirit of Waves and Tides
Spirits of the Elemental Plane of Water form shapeless liquids into water elementals, aqueous beings with the might of surging waves. Water elementals are as mutable as liquid, allowing them to crash into foes and seep through narrow cracks. They can crush foes with limb-like geysers, or they might flood over creatures, submerging and drowning foes within their whirling forms. Water elementals often appear near nexuses of elemental power, such as aquatic abysses, magical springs, and whirlpools.
Water elementals' shapes are influenced by the liquid bodies in which they form. Roll on or choose a result from the Water Elemental Compositions table to inspire a water elemental's features.
Water: greatest of the elements in might and form. A tsunami's torrent. A blizzard's claws. A parent's tears. What is not moved by water?
5e Tools
Roiling waves of water that fall upon creatures only to reform
Water elementals resemble roiling waves of water, which seem to fall upon any creature attacked, only to reform the next round. They take double damage when attacked with air or wind attacks (including air elementals). A water elemental cannot move more than 60' from a body of water. They do an extra 1d8 points of damage against creatures, vehicles, or structures which are in the water.
Basic Fantasy Role-Playing Game
Beings formed of pure, elemental matter (air, earth, fire, or water) that can be summoned from their plane of origin to serve a magic-user.
OSE
Roiling waves of water that fall upon creatures only to reform
Water Elementals are creatures from the Elemental Plane of Water, though they may sometimes be found elsewhere. When encountered on the Prime Material Plane, usually as a result of summoning magic, they take the form of a great wave of water or other liquid, constantly in motion, but retaining an almost humanoid shape. Some claim that they have sea green eyes, of a sort, and others that they were able to discern a mouth. Like others of its kind, though, it rarely responds in kind when spoken to, its language being heard only in the crash of waves.
OSRIC