D&D 5E 5E underwater thoughts

tglassy

Adventurer
https://m.youtube.com/watch?v=BONzS8i86bw

Thank you for degrading others for an apparent lack of physics knowledge while showing yours to be a fact.

Fire isn’t doused by water because water is cold or because it absorbs heat. It is doused because water effectively cuts off the oxygen supply. If fire has its own oxygen supply, it will still flame, even under the water. Since the material components of the spell are a tiny ball of bat guano and some sulfur, and oxygen is not listed as being needed to cast it, it can be assumed that the spell provides everything it needs to make the flame, including its own oxygen. If that was the case, it would still flame, still streak under the water, and still erupt. There might be a size difference, as the water lowers the range of the area of effect, but the flame would still happen, for an instant, causing the water to flash boil. If this is the case, it would even flame and erupt in a vacuum, as it provides its own oxygen. It wouldn’t last long, and wouldn’t go far, but it would still erupt.

As for water being denser than wood, it is also a liquid, and therefore easier to travel through than wood. A bullet goes further in water than it does in solid wood. Even a bullet shot from outside the water goes further, because regardless of density, a liquid is easier to move through than a solid. An arrow flows through the water easier than a bullet, and crossbows can even be used underwater in the game.

As another point, it’s a freaking magical spell. By its very nature, it breaks the laws of physics. The answer to whether it works underwater or not is determined by HOW it is breaking those laws of physics. Which is determined by the DM. If some wizard decides to design a spell that creates flames that provide heat and light underwater without being doused under the water, how is that more fantastical than creating a magical eye sensor that he can somehow psychically see through, or warping time and space to create his own plane of existence, then creating a clone of himself, filling the room with a copy of his spellbook and then making a gem from Drawmji’s Instant Summons for all his most important belongings, leaving the gems in that demiplane, so that if he dies, regardless of in battle or of old age, his soul is transferred into a 20 year old clone of himself who has immediate access to all his equipment and spellbooks. But that’s perfectly in game legal. Making a fireball underwater? WTF! THAT BREAKS THE LAWS OF PHYSICS!




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OldFool

First Post
The problem is what is obvious to some is not to others. So that "do not cross this is :):):):):):):):)" line is not in the same place for different people. So to be a fireball boiling off water is completely ludicrous. But for others... it's cool.

I have no problem if people think things are cool and want them to happen that way in their campaign. Go for it. But please don't try to use physics to support your position in a fantasy game unless your physics are strong, grasshopper. And I salute your use of the Rubber Bible in your argument.
 

Ancalagon

Dusty Dragon
Note that the average damage from a fireball is enough to insta-kill human commoners, most medium-sized animals, and some 1st-level PCs, even if they make their saving throw. For larger animals, the damage on a successful save is often enough to drop them to 0 hit points, even if it doesn't kill them outright. So, that's pretty close to "death no save."

Killing commoners and low level PCs... that describes pretty well the power of a grenade, mortar round or small artillery shell. Flash boiling a 40 feet diameter sphere of water requires the energy output of a small tactical nuke.

Could a fireball blowing up in the air over a body of water flash boil a thin layer of water on the surface of said body of water? Create a steam cloud? Sure! But the whole sphere requires *massive* amounts of energy.

PS: Flashboil is way, waaaaay more damage than killing.
 
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Ancalagon

Dusty Dragon
https://m.youtube.com/watch?v=BONzS8i86bw

Thank you for degrading others for an apparent lack of physics knowledge while showing yours to be a fact.

Hello

I would like to start by noting I only saw this post of yours today. You seem... rather annoyed. I'm not sure if it's in response to something I said or someone else. I hope we can talk about this without rancor, and I will do my best not to be snippy.

Fire isn’t doused by water because water is cold or because it absorbs heat. It is doused because water effectively cuts off the oxygen supply. If fire has its own oxygen supply, it will still flame, even under the water. Since the material components of the spell are a tiny ball of bat guano and some sulfur, and oxygen is not listed as being needed to cast it, it can be assumed that the spell provides everything it needs to make the flame, including its own oxygen. If that was the case, it would still flame, still streak under the water, and still erupt. There might be a size difference, as the water lowers the range of the area of effect, but the flame would still happen, for an instant, causing the water to flash boil. If this is the case, it would even flame and erupt in a vacuum, as it provides its own oxygen. It wouldn’t last long, and wouldn’t go far, but it would still erupt.

You are quite correct that some fires can burn under water, this is a well known fact. I will note that quano has a high content of potassium nitrate (or is *commonly believed* to be so), which acts as the oxidizer - the spell material components are actually a sort of reference to the recipe for black powder. If you were trying to argue that a fireball would work in space, I would agree with you.

However, this is the part I cannot agree with: "causing the water to flash boil". As I demonstrated above, boiling a 950 ton sphere of water takes *enormous* amounts of energy. Could a spell provide that much energy? Sure? But it would be be a much higher level spell, and do waaaay more damage. This is the core of my argument.

I also have rebuttals for how water works to suppress fires, water and bullets etc etc, but that's peripheral, and I'm not interested in "wining an argument on the internet" if it makes you angry.

As another point, it’s a freaking magical spell. By its very nature, it breaks the laws of physics. The answer to whether it works underwater or not is determined by HOW it is breaking those laws of physics. Which is determined by the DM. If some wizard decides to design a spell that creates flames that provide heat and light underwater without being doused under the water, how is that more fantastical than creating a magical eye sensor that he can somehow psychically see through, or warping time and space to create his own plane of existence, then creating a clone of himself, filling the room with a copy of his spellbook and then making a gem from Drawmji’s Instant Summons for all his most important belongings, leaving the gems in that demiplane, so that if he dies, regardless of in battle or of old age, his soul is transferred into a 20 year old clone of himself who has immediate access to all his equipment and spellbooks. But that’s perfectly in game legal. Making a fireball underwater? WTF! THAT BREAKS THE LAWS OF PHYSICS!

Sent from my iPad using EN World

This is more of a philosophical difference at this point than a physics one. I can't claim to be right here. But I will note that, from my perspective, we sort of have to assume that the normalish laws of physics apply (gravity pulls down, ordinary fire needs oxygen, mass is constant etc etc), until magic intervenes. Fireball creates a very short-lived sphere of fire, which then interacts with the environment. If you want to have "fireball does damage under water because it's magical!" Sure! It's your game, and why not, it is magic. If you say it flash boils 950 tons of water, then... that's harder to defend, and raises a lot of questions (does it flashboil everyone inside too? Perhaps water is easier to boil on this universe? Elemental lords get involved?)
 
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cbwjm

Seb-wejem
I think I'd pretty much just run with "You're underwater, fire spells don't work." Other spells might be affected on a case by case basis. If I really wanted to get some more rules I might look at plancescape to see what restrictions/alterations they had on spells being used on the plane of water which could be transferred to underwater in general.
 

Uchawi

First Post
I would create two different areas of knowledge or domains based on the laws of water and air and then any weapon or spell must be specialized towards one or the other. Then you can apply global modifiers where a water based two hander does less damage or has disadvantage to hit in air born setting, or vice versa. Apply the same concept to cantrips, spells, potions, armor, etc. Magic or master craft items may work equally well in either environment. Hopefully that simplifies the entire physics debate.

Other questions may need to be answered for what a water born creature needs to gain a short or long rest in the air realm (which is hostile and unforgiving) and vice versa. Same concept applies to eating and sleeping. Healing can be equally as challenging (as one side requires saline/water and the other air).
 

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