Can spells with a verbal component be cast underwater if the caster can't breathe water?

Question

My party recently tipped over a boat of enemies into what was essentially rapids and trapped the enemies in a cube of force underwater. The warriors inevitably drowned as they had no way out. However, trapped in the cube of force was a wizard with access to a teleportation spell (Misty Step) with a verbal component. Could the wizard use his spell with a verbal component underwater and escape a watery death? If the rules don't specify anything about verbal components underwater specifically, have any of the designers mentioned anything about this?

Note: as a 5e DM I made a ruling on the spot (decided to allow it on the condition that the caster goes directly from "holding breath" to "suffocating") so I am aware that it's within my power to decide how it works in my world. I'd just like to know if the rules or someone wiser than me has addressed this yet.

Answer 1

Yes

To play Devil's Advocate here, it is not strictly RAW to disallow spellcasting. Of course, it is a sensible house rule -- but it would be a house rule if you disallowed it.

Jeremy Crawford says you can

This tweet from Jeremy Crawford explicitly states that being underwater doesn't interfere with spellcasting. There is no conditional "Yes, if they can breathe underwater"

JC says you can, but only if you can breathe underwater?

Another tweet from Jeremy Crawford says that, if you can breathe underwater, you can perform the verbal components of spells. Fair enough. However, this is NOT the same as "if you can't breathe underwater, you can't perform the verbal components of spells" either.

Just as saying "if you can sing, you have a voice" is true, but "if you can't sing, you don't have a voice" is not necessarily true. Again, strictly speaking, nothing is disallowing spellcasting here yet.

The PHB says you have to be able to talk?

As @NautArch has shown, the PHB does mention a rule on V components of spells that seems like it should affect spellcasting.

Most spells require the chanting of mystic words. The words themselves aren’t the source of the spell’s power; rather, the particular combination of sounds, with specific pitch and resonance, sets the threads of magic in motion. Thus, a character who is gagged or in an area of silence, such as one created by the silence spell, can’t cast a spell with a verbal component.

This question on Quora asks if we can talk normally underwater. Well, the answer is yes, we can speak normally. The question is just, can the person you're speaking to understand you?

Well, in spellcasting, nobody needs to understand you. You just need to produce mystic words that form a combination of sounds, with a specific pitch and resonance. Note that you can always do this underwater, it's just that the sound is formed in your larynx and becomes distorted as soon as it touches the water. But the rules don't say "the sounds must reach outside your larynx" or "others must hear you clearly". You can technically still do it.

Moreover, every spellcaster will likely have different ways of casting the same spell, just because they naturally have different voices. It is not against the rules to consider that there are multiple ways you can set pitch and resonance, but still cause the weaves of magic to be set in motion in the same way. So, sound can still travel through water. Why can't a magic user speak those mystic words in a way that, when the sound travels underwater, the specific pitch and resonance still matches what is needed to pull off the spell? RAW, this is not illegal.

But Gagged prohibits spellcasting, so why doesn't being underwater?

There are many ways to wave this away. Any answer I give will not be RAW, and is in DM fiat territory absolutely.

Nonetheless, you can argue that when you are gagged, your tongue cannot move about and you cannot shape the sounds and words precisely because of this, whereas being underwater does not forbid this.

You can also say that being gagged restricts your jaw movement, but being underwater doesn't, so you still retain enough control to be able to cast while submerged.

Sensible House Rules

Casting underwater is different from casting in air, this is true. How you handle this is up to you. This Enworld discussion shows a few ways other DMs handle it, in the order of their appearance in that thread:

• Spellcasting is totally disallowed underwater unless the caster can speak underwater
• Allow spellcasting underwater without penalties, as there is no rule actually forbidding it
• Have the caster perform a check. On a failure, the spell slot is not wasted, but the action is lost. But only do this if: 1) there was a way around this issue, or 2) being in the water is intended to be a penalty. Otherwise, just let the casters cast normally.
• If spellcasting is penalized underwater, non-casters must be similarly penalized
• Allow one spell to be cast, but then immediately have the caster start drowning
• Require a concentration check before casting a spell
• Disallow spellcasting for a one-off encounter, but allow it if the characters are expected to be under the water for extended periods

Another definitive JC Tweet:

You can cast a single spell underwater, but afterwards you begin drowning if you can't breathe underwater. Otherwise, no rule prevents verbal components from working underwater. Thanks to @mxyzplk for bringing this tweet to my attention!

Extra Note: In that Twitter thread, Dan Dillon asks:

Is the intent that if you cast a verbal component spell you're no longer holding your breath (and now on Con mod +1 rnds)?

To which Jeremy replies "yes." But technically it is Con mod rounds only, without the +1. The +1 only happens when you've held your breath and have Con mod + 1 minutes before you start drowning.

Answer 2

No, they can't

Verbal components (PHB, 203) for spellcasting as described as:

Most spells require the chanting of mystic words. The words themselves aren’t the source of the spell’s power; rather, the particular combination of sounds, with specific pitch and resonance, sets the threads of magic in motion. Thus, a character who is gagged or in an area of silence, such as one created by the silence spell, can’t cast a spell with a verbal component.

Gagged is very similar to being underwater in that you have the ability to make sounds, but they are muffled/distorted. This distortion seems to be enough to make the Verbal component fail based on the above quote. And it actually meshes with physics in that pitch and resonance are altered by water (and the container it is in.)

Unless they can speak underwater, then this is a NO based on the similarity of verbal communication while gagged and underwater.

Answer 3

I have actually used the gag order as an underwater mechanic. So I had the party use potions of water breathing or a water breathing spell to be able to stay underwater, the verbal components were gagged due to the breathing apparatus created by the spell and potions. The fact that the spell does not just describe how it works underwater, I used the homebrew rules to describe that the spell had a mouth component that could be described as a gag. Other adventurers had water breathing and they were able to cast verbal components under water, and those with a waterbreathing cap or cloak of Mantis did not have the mechanism in the mouth so they too were not gagged and could use verbal components under water. It made for an interesting time in the ocean...

Answer 4

Yes you should be able to in my opinion, as an above poster mentioned the water doesn't actually stop you from being able to talk or generating the pitches needed to cast a spell.

While you are talking underwater, from the point the air goes through you vocal box, and the sounds are shaped with your tongue and lips all the way up to hitting the Water outside of your mouth it is going to sound exactly as it does out of water. (While you talk you're going to generate a bubble of air in front of you that the sound can travel normally a little ways through.)

After it hits the water the sound losses most of its energy due to the much higher impedance of water compared to the sound in air. (It's still there though and the same exact pitch, just very quiet and harder for us to hear because our ears work differently under water.)

But the point still stands that until it hits that water it sounds 100% the way it does normally, out in air including its volume.

Now what should be noted is there is nothing that says verbal parts of spells need to travel any specific distance outside of the body to actually work. But a DM can decide a distance if they want.

Every DM is different, but to be honest if you don't let someone cast a spell underwater because it doesn't travel far enough and loud enough to work, then by the same logic you shouldn't let someone cast a spell that they mumble under their breath. Because the same idea would apply about the spell not traveling far enough or at least doing so at a loud enough levels.

My personal thing is knocking 30 seconds off their air for speaking the spell underwater. Some people do instantly starting to drown which seems a little excessive to me. (Though someone with a low con might still which is fine by me :p)

Now the difference between water and a gag is the gag stops you from utilizing your tongue and lips to shape the spell which being underwater does not. That's why gags stop you from speaking spells at all.

This of course is my take on it, but as I said you can speak unhindered underwater. This isn't a a theoretical statement, it is actually completely factual and something you can confirm with a quick search and a few pages of reading.

Good luck.