Water elemental
From Ardrana
Water elementals are natives of the Elemental Plane of Water. Like all elementals, they are made of the stuff of their plane, and are not readily tangible to the inhabitants of planes other than their own.
Water elementals can be conjured in any area containing a large amount of water or watery liquid. At least one thousand cubic feet of liquid is required to create a shell for the water elemental to inhabit. Usually a large pool serves this purpose, but several large kegs of wine or ale will do just as well.
The water elemental appears on the Prime Material Plane as a high-crested wave. The elemental's arms appear as smaller waves, one thrust out on each side of its main body. The arms ebb and flow, growing longer or shorter as the elemental moves. Two orbs of deep green peer out of the front of the wave and serve the elemental as eyes. Like all other common elementals, water elemental rarely speak on the Prime, but their voices can be heard in the crashing of waves on rocky shores and the howl of an ocean gale.
Note: Water elementals originally appeared in this form in the 2nd Edition Monstrous Manual for the AD&D game from TSR. Their use here is for the purposes of providing context for the campaign only.