FREQUENCY: Very rare
FREQUENCY: Very rare ([Dungeon Level VII])
FREQUENCY: Common ([Ethereal Plane])

NO. APPEARING: I
ARMOR CLASS: 2
MOVE: 6"//18"
HIT DICE: 8, 12, or 16
% IN LAIR: Nil
TREASURE TYPE: Nil
NO. OF ATTACKS: 1 ~ 12 (HD 8) | 9 (HD 12) | 7 (HD 16)
DAMAGE/AttACK: 5-30
SPECIAL ATTACKS: See below
SPECIAL DEFENSES: +2 or better weapon to hit
INTELLIGENCE: Low
ALIGNMENT: Neutral
SIZE: L
LEVEL/X.P. VALUE: VII | 2850 + 15

SAVES, 8 HD: 10.11.12.12.13
SAVES, 12 HD: 7.8.9.8.10
SAVES, 16 HD: 4.5.6.4.7

Water elementals are, for all practical, purposes, limited to water
operations, for they can stray only 6" from their element. It normally
requires a considerable volume of water (or watery liquid) to create a
water elemental -a pool of water of at least 1,000 cubic feet in volume,
but several large barrels of ale or wine would suffice. Outside their
element water elementals are less effective, and they lose 1 point from
each die of domage they inflict. In a body of water they attack at full
effect, move more swiftly, can upset small craft (1 ton of craft per hit die of
elemental), or slow or stop craft (1 ton of vessel can be stopped per hit
point of elemental; if greater tonnage, simply ratio the tons to hit points to
find the rate the vessel is slowed).

There are many other elemental forms on the plane of water. Free-willed,
intelligent beings are common as well as much more powerful elementals
of the sort dealt with here. It is possible that they are ruled by a god-like
king.

(see also Triton and Water Weird)
 

At that time elementals were rubbery dime store critters about 65 mm scale, each vaguely reminiscent of the element it represented, the fire figure a red and orange, the water one shades of blue, Can't recall the color of the air one, but it was whirrled I think. The earth elemental figurine was sort of man-like and lumpy perhaps. Memory begins to fail me after some 35 years.

Cheers,
Gary

Elementals: Creatures of the plane of water seem to be made
up of currents of watery forces, making them hard to detect in
their native element and obvisou in shape only when they are
placed in a pocket of air or similar medium that confines them to a
specific shape. In +addition+, the appearance of a type of elemental
creature (such as the elemental elephant in the preceding table)
can very from one encounter to the next, though it has the same
stats. For help in determining random looks for elemental creatures
(as opposed to "you see a watery elephant"), the DM is
directed to page 120 (Appendix II). <>

    Most elemental creatures of Water prefer the deep areas of the
plane that are unsilted by debris and far from vortices. Elemental
creatures are easily drawn into such vortices and cannot easily
escape, so they avoid these traps if at all possible. One group of
water elementals, the tritons, have made excellent progress in
settling large areas of the Prime plane oceans.

Source = Manual of the Planes