Were-Elemental (Water)

Very interesting, and I like it at first glance.

Lunar Body does not grant the (Aquatic) subtype, so you can't breathe underwater... despite being a were-water elemental. That could be a problem, though I'd understand giving something like Hold Breath at first level and full water breathing later.

In Alternate Form you never specify that the full elemental form cannot speak, but add it as one of the things the hybrid can definitely do, which should be clarified. Otherwise I don't have a problem with it.

In Water Elemental Empathy your first use of the word "Animals" and the use of the word "Beasts" should both be "Creatures".

Wave Sense allows you to gain "Tremer-Sense", which should be "Tremorsense". Otherwise okay, requiring you take full elemental form for very short range but nigh-undefeatable (except for flight, which would either be as easily seen by you as anyone else or be invisible, in which case anyone without see invisibility or a similar effect is screwed, not just you) sense is fine by me.

Whirlpool may be slightly overpowered for level one, but it is situational and short-duration, so it isn't significantly so. You use "Whirlwind" at least twice. The kicking up of debris wouldn't always apply upon hitting the bottom of a body of water, and might apply at other times. Make it whenever the Whirlpool passes through debris, and the effect disperses 1d4 rounds after leaving the area of debris. Also, in the text you say the Save DC is Strength-based but the table says Constitution, that could use a clarification.

I assume the ally saving someone can only occur if they threaten the space holding the unconcious person in Drown. Might want to have an opposed grapple check on there (thematically appropriate, and you can give the WE(W) a penalty if it would be too powerful), though it's not nearly necessary. You don't explicitly mention that the opposed Swim vs. Grapple check is to escape the Drowning, nor do you mention what the Will save does at all (apart from to "regain focus", which doesn't mean anything), nor do you mention that a concious person can attempt to escape each round or that anyone else can help them. A cool ability, but the wording needs to be tightened up a lot. You've got the same as the much-mocked drowning rules for hit points, this can (sort of) heal people. I'd also like to see a version that functions in Hybrid form, perhaps at Huge size and larger.

I'd suggest having Flow as a swift action at first, becoming a free action at 8 HD or something similar. Otherwise a fine ability!

In Magucanthropy, well I'll bold the appropriate sections and unclear sections:
Curse of Magucanthrope: At fourth level the Were-Elemental (Water) can transmit Magucanthropy to other creatures. If a Humanoid or Giant of (the same sizes as the Prerequisites for this class) is hit by the Were-Elemental (Water)’s natural attacks while it is in either Alternate form, the struck creature must make a fortitude save (DC 10+1/2 the Were-Elemental (Water)’s HD+ Constitution modifier) or contract Magucanthropy. Magucanthropy Functions exactly as Magucanthropy except as noted above. For more information on Magucanthropy, check the Lycanthrope entry in the monster manual.
Some of those should be Lycanthropy, I think. A bit trigger happy with find-replace?

A fine class, but the wording needs a lot of work, even if it is just small things. This may have been the wrong thread, if it is then tell me.

That's the last review I'll be doing today, but as of now, I start work on the Gargoyle.