Need help with Elemental Room ideas.

[Agrias]

So I was thinking of making a room with a pool. On the bottom of which there is a needed key. The catch is that the water is one giant water elemental that wont let the players get near it. I dont want it to be a combat encounter though so the elemental just pushes players out of the room by shooting water.
Was thinking maybe there ll be some ways to change the guardian's element to, for example ice, fire, earth, wind, acid etc. And that somehow would help getting the key but honestly cant see how would that work to make sense.
I would be grateful for any interesting ideas to how players could get the key out?
Anything goes pretty much since it's a mage tower room exposed to limbo realm.

[Darth Ultron]

You could just make it ''animated water'', but not a creature. So it would be a swim check vs the 'current' of whatever DC is good. Or the Pc's can come up with a clever way to 'sink' to the bottom. Or made anchor a rope to the bottom and ''climb down the rope underwater'', so a climb check vs the DC. You could even go for ''fishing the key out'' using a hook and line, that would be a Slight of Hand DC to not disturb the water...or even a Profession(fishing) check.

You can also have ''animated air'', basically a gust of wind type spell, to push people out of the room.

With magic, anything can ''make sense'', and there are ''elementals'' of everything.

[Gildedragon]

Ideas:
Massive stone switches on the walls. A reflex save to get the water to try and bludgeon them and hit the switches instead.

Resisting the watery bull rush for a couple rounds drains the pool. It becomes a time for the party to be all Aid Another to the strongest, heaviest PC.

[Inevitability]

There's a pouch of Dust of Dryness located somewhere in the room/dungeon, which instantaneously kills the elemental.

There's a trio of elemental gems (fire, air, earth) to be found somewhere in the dungeon, with an inscription making clear they can be used to neutralize the elemental. Depending on what gem is used, a different hazard will appear.

Fire: The pool will turn to boiling steam and expand rapidly, potentially scalding all nearby creatures. However, the steam will rapidly cool leaving the key available.

Earth: The pool turns to thick mud. It's no longer a threat, but must be emptied manually (or the party cleric could summon a celestial badger to dig the key up).

Air: The pool freezes over. Shattering the upper layer causes a geyser of icy water to erupt, but leaves the pool empty afterwards.

[denthor]

Take a look at a zero level wizard spell called mage hand it picks up objects that are non magical and less than 5 pounds. Decide if this would work and just leave a sign hand from a mage is needed. Where the key goes and in all access points to where the key is.

Since you want it to be non combat have the pool non magical 20 feet deep and cold and clear. If the players are low level this would be a challenge . They could over come with the above spell.