# Is there any obstacle to using a Mage Hand in water?

How does water affect Mage Hand? I know there are rules regarding disorientation with ray spells, and use of fire under water. But if a person wanted to, for example, grab some keys from a well, would there be obstacles to overcome for using mage hand?

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Do you want a Rules As Written answer, or how it might be reasonably interpreted? – C. Ross Jul 7 '13 at 23:16
I wouldn't mind both, if possible. Read is Written, as well as how someone might allow its use – Arraetrikos Jul 7 '13 at 23:29
I don't believe the written rules concern themselves with this. A "common sense" or physics-based answer, such as @Emrakul's, is probably the only one that is possible. – SevenSidedDie Jul 8 '13 at 1:29

Looking at the details for Mage Hand (from the d20PFSRD):

Target: one non-magical, unattended object weighing up to 5 lbs.
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Description: You point your finger at an object and can lift it and move it at will from a distance. As a move action, you can propel the object as far as 15 feet in any direction, though the spell ends if the distance between you and the object ever exceeds the spell's range [of 25 ft. + 5 ft./2 levels].

There are no official rules, at least as far as I know, for the pressure of water on Mage Hand. However, it's possible to estimate the force of the water on the moving keys, if you're fantastic with your fluid dynamics. Supposing, though, that not everyone is an engineering major... My comment above:

Since Mage Hand has no mass, it's only fighting the mass of the keys. Thus, the sum of the weight of the keys and the normal force of the water can't exceed five pounds. It's very likely to just move slower.

However, there are many ways to read the rules. Mage Hand breaks if it encounters a solid object, so you could just say it fails underwater. You could also read the rules explicitly; since the object is under five pounds, you can move it fifteen feet in any direction, obviously unless it's obstructed.

GM's call.

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To be unnecessarily pedantic: the Mage Hand is fighting the weight of the keys, plus the "water friction" that comes from displacing water due to moving the keys. This is exactly the same as the air friction that Mage Hand normally goes up against, it's just stronger (because water is heavier and more viscous than air). – Paul Marshall Jul 8 '13 at 19:08