okay, im kind of confused as to why fire magic doesnt work underwater, because all magic is, is the manipulation of mana to acheive a goal. so wouldnt the fire spells just convert to steam? and still do burn damage?

Steam is a seperate Elemental Effect from Fire. (IMG:style_emoticons/default/nyahnyah.gif)
Fire based magics (specifically Elemental Effects) are subject to environmental conditions as per SR4 p154-155. Though this only relates to the secondary effects.
Indirect Combat Spells "travel" to hit targets, and are interrupted by Barriers. Since you could easily count water as a semi-transparent barrier with a specific of dousing fire I would have to agree that fire based Elemental Effects dont work underwater.
Someone needs to make some spells that are Direct Combat with Elemental Effects (Spontaneous Combustion) .
Thats just my 2 (IMG:style_emoticons/default/nuyen.gif)

you bring forth the fire from your fingertips only to be scalded by boiling water.

Just remember that magic doesn't follow the laws of physics. The fireball spell doesn't create heat, it creates fire, and fire gets extinguished under water, ergo no fire under water.

Not necessarily. Magnesium and White Phosphorus burn underwater. Why not a mana fueled firebolt?

Becomes your mage doesn't believe that fire can burn underwater.

And WP does not burn underwater. It goes out, but lights again when it is re-exposed to oxygen.

Thermite on the other hand ...

Burns really fucking hot. In fact, it's ignition temperature is hot enough to boil water. However, the main point is that thermite supplies its own oxygen to burn.

If thermite is ignited underwater, the molten iron produced will extract oxygen from water and generate hydrogen gas in a single-replacement reaction. This gas may, in turn, burn by combining with oxygen in the air bubble generated.

SO, if our mage in question were aware of this fact, they might be able to wrestle a thermite reaction into existence - at least under my houserules.

Knowledge: Chemistry to see if he knows the proper chemical formula for thermite.

Why? Does your Shaman have to do a Knowledge: Anatomy to cast a healing spell? Does your mage have to do Knowledge: Optics to cast an illusion spell?

Because you're trying to subvert a known law of magic: Fire Does Not Work Under Water. Therefor you need to know something about chemistry in order to duplicate the abnormal effect.

Also, Fireball and Thermiteball are different. Fireball MAY ignite flammable materials, and is subject to half impact armor for soak rolls.

I can guarantee you that a thermite fireball WILL ignite flammable materials, and many traditionally non-flammable ones (such as thin metals), and sure as hell won't be noticably impede by impact armor.

Or, to put it another way, you can cast a thermite fireball, but only if you're casting at like, force 20. Because otherwise your fire is nowhere near hot enough.

Arsenal p.171 "Underwater Magic".

Well if "fire" magic won't work under water, doesn't that mean that "earth" magic won't work in the open air?

air doesn't extinguish rock. also, the sensible temperature of water can't be raised over 212 degrees until it boils away(if contained, the vapor can be superheated), there will be latent heat build up, but the thermal energy will be used to turn water into gas and will diffuse through the volume of water. so if you're talking about the puget sound. thats a pretty big heat sink.

Unless the heat produced is significant enough to overcome the thermal transference of water. I.E. thermite (water can't shunt 4000+ degrees F of heat fast enough, a pocket will boil).

But we're not talking physics, we're talking magic law. Fire and Water are opposites, one destroys the other (at least in the hermetic tradition) so it is somewhat reasonable to assume that fire spells wouldn't work underwater any better than water spells would work inside a firestorm. Fire being a chemical reaction rather than an actual physical substance it's kind of hard to find an equivalent to underwater for fire, but air and earth don't have that problem. Both air and earth are physical things that can be engulfed by the other. And Air and Earth are magical opposites (in the hermetic tradition at least) so they destroy one another.

So...

If a mage standing on the bottom of a swimming pool can't cast a fire spell because he's engulfed by water, fire's opposite, then why would a mage standing on the top of a building (or on the ground for that matter) be able to cast an earth spell when he's engulfed by Air?

Water -> Wood -> Fire -> Earth -> Metal -> (Water)

What air?

5 element theory makes so much more sense than 4 element theory.

Oh yes, the destructive cycle:

Water -> Fire -> Metal -> Wood -> Earth -> (Water)

Except that in SR Canon, it's very clearly the 4 elements of Air, Earth, Fire and Water. There aren't wood elementals or metal elementals. Those would likely manifest as hearth spirits or forest spirits.

It might not be SR canon, but the theory makes more sense.

It is canon- it's just not Hermetic.

Wood is Plant, but Metal what would be?

so, in other words, no, or at least as long as theres a chem major in the group... or if you have a lienent gm.

and could i make a theremite ball spell, or would it just be easier to buy a shitton of thermight, and burn thekara/ bp for demolitions?

metal its a spell element so a guess you could change an earth elemental a bit to make a metal one.