What happens to lightning spells underwater?

As the old adage goes “water and electricity don’t mix” because in real life water has impurities in it that make it super conductible. So what would happen in D&D if, for instance, a sorceress cast shocking grasp on a creature underwater?

Would the spell not work? Would it affect the caster as well? Would it spread and hit everything under water?

Shocking grasp in particular specifies that “You have advantage if the target is wearing metal armor” which indicates that they are taking conductivity into account.

What about call lightning or chain lightning, would casting a higher level spell change the outcome?

Is your movement penalized underwater if you have a swimming speed but choose not to use it?

Here are the rules on underwater movement:

While climbing or swimming, each foot of movement costs 1 extra foot (2 extra feet in difficult terrain), unless a creature has a climbing or swimming speed.

I have a question related to the highlighted passage: if a creature has a swimming speed, but chooses not to use it, would their movement be penalized as per the above rules, or would they get the same benefit [no speed reduction] that creatures using their swimming speed have?

One case where this would be useful is if a character has a walking speed of 50 feet and a swim speed of 30 feet. Since the character has a swim speed, can it use its walking speed to move faster (since it no longer has to spend extra movement)?

Does a bronze dragon’s wing attack work underwater?

An adult bronze dragon has a lair deep inside of a coastal mountain. To get to where she hides her stuff (and where she is keeping a clutch of eggs warm) an adventuring party needs to swim deep underwater, then through a water-filled passageway, and then up to emerge on the surface of a lake inside of the mountain (they end up inside a very large dome, roughly).

If the dragon detects them before they surface, and leaps into the water (she has a swimming speed of 40) can she successully use her wing attack (a Legendary Action) against the party while fighting underwater?

The dragon beats its wings. Each creature within 10 feet of the dragon must succeed on a DC 20 Dexterity saving throw or take 14 (2d6 + 7) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

My instinct is that she cannot use the wing attack, and I don’t think that she can "fly" in the water (for half of her flying speed) by beating her wings. Whether or not dragons swim by using their wings, or if they move more like a sea serpant, is unclear but I tend to believe the latter.

Underwater Combat rules leave me little to work with. The restrictions are

When making a melee weapon attack, a creature that doesn’t have a swimming speed (either natural or granted by magic) has disadvantage on the attack roll unless the weapon is a dagger, javelin, shortsword, spear, or trident. A ranged weapon attack automatically misses a target beyond the weapon’s normal range. Even against a target within normal range, the attack roll has disadvantage unless the weapon is a crossbow, a net, or a weapon that is thrown like a javelin (including a spear, trident, or dart). Creatures and objects that are fully immersed in water have resistance to fire damage. (Basic Rules, Ch 9, p. 80)

She has a swimming speed, so her tail attack or her bite attack are not at disadvantage. Her Wing attack doesn’t seem to be either of those to attack categories since it requires a dexterity saving throw.

Does the dragon lose her ability to use that legendary action, Wing Attack, if she is fighting underwater?

(While I am also puzzling over what ‘prone’ means when somoene is swimming underwater, I don’t need that answered for the purposes of this question)

What would happen if you opened a Bag of Holding underwater?

I’m in a naval campaign where some of the game could take place underwater, and I could reasonably acquire a Bag of Holding soon, so it would be nice to know before I try to grab an item underwater and jettison all of my gear into the Astral plane. Would it fill with water until the bag was filled to capacity and scatter all the contents inside as well?

Also assuming you didn’t break the Bag of Holding by overfilling it to capacity, would putting water inside it get other objects inside wet, potentially ruining them?

Do crossbows and other noted exceptions miss past their long range underwater?

The rules is written as

A ranged weapon attack automatically misses a target beyond the weapon’s normal range. Even against a target within normal range, the attack roll has disadvantage unless the weapon is a crossbow, a net, or a weapon that is thrown like a javelin (including a spear, trident, or dart).

My question is if this part:

A ranged weapon attack automatically misses a target beyond the weapon’s normal range.

Is a complete clause on its own independent of the next sentences, or is a part of the later sentences. Do all ranged weapon attacks miss past their normal range, or only weapons that aren’t listed as exceptions?

Does sovereign glue work underwater?

I stumbled across an incredibly vicious trap. (Seriously, whoever came up with this, they need help)

In the bottom of a well contains water 20 feet deep. At the very bottom of the well, a sword sticks out of a pile of debris, hilt up. Scattered across the floor of the well are piles of bones. If a character tries to grab the hilt of the sword, they find that the hilt is covered with Sovereign Glue. To pull themselves free from the sword, stuck in the bottom of the well requires a DC Strength Check…

My question is, is there any source that says that Sovereign Glue would dissolve in water or any other liquid? Would this substance work as the trap is written?

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

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.

How does underwater rules work with flying familiars?

I will soon run the Underworld Speculation adventure with my group of players and two of them have flying familiars. An owl and a pseudo dragon.

Is there something in the rules that states that a familiar or a flying familiar can’t be used in water ?

There isn’t any rule change or anything about underwater fight and exploration. PC group is able to breath underwater thanks to a NPC that casts Water Breathing.

Does the Scent ability function under water in conjunction with the Aegis’ Underwater Breathing Astral suit option?

Does the Scent ability function under water in conjunction with the Aegis’ Underwater Breathing Astral suit option?

PC in party is an Aegis 4, Druid 7 and managed to get the scent ability, wonders if he can track by scent under water using the that suit option.

Underwater Breath: The aegis can safely breathe underwater as long as he is wearing his astral suit.

https://www.d20pfsrd.com/alternative-rule-systems/psionics-unleashed/classes/aegis/astral-suits