I haven’t posted here in a while. I have been working on 5E Ship-to-Ship combat rules. They will be finished soon. In the mean time here is part that may be of general interest.
Drowning Rules for D&D 5E
Falling Off the Ship
Rough water adds 5 to all the following DCs except for checks made when more than 5 feet under the surface. Flotsam or other floating items grant advantage to checks to stay afloat.
The Fall
This can be hazardous to your health. If you fall overboard you will splash down 1d6+5 feet from your ship. If you are pushed overboard you will fall 2d6+5 feet from your ship. If you jump or dive into the water you can enter the water at any point up to the maximum distance you can jump (refer to the Jumping rules in the Player’s Handbook). If you fall or are pushed overboard, you must succeed on a DC 10 Dexterity (Acrobatics) check to enter the water without damage. Otherwise you receive 1d6 hit points damage from the fall.
Swimming
Each foot you swim cost you one extra foot of speed. If you are within 5 feet of a moving ship (or one that has been involved in a ramming or grappling maneuver), you must make as DC 10 Strength (Athletics) check. Failure means that you cannot move this round, you are using all of your strength to simply keep your head above the waves. Once you reach the ship, you must make as DC 15 Strength (Athletics) check to climb back onto the ship. Failure results in you falling back into the water.
Underwater
You can swim underwater as long as you can hold your breath (see “Drowning” below). Your underwater swimming speed is the same as your surface swimming speed. You can swim straight down at half that speed. You can swim straight down at 15 feet per round if holding the equivalent of medium armor, or 25 feet per round if holding the equivalent of heavy armor. If unencumbered, you can swim straight up at 20 feet per round.
Armor
In general, heavy armor is not terribly common on ships. The weight tends to be the most prohibitive factor – falling overboard in 65-pound full plate normally results in death. Occasionally, combat Infantry will don light or medium armor for a battle, but most of the time sailors go unarmored. A lucky few (usually the PCs and important NPCs) have magic items that improve their AC, but most sailors rely on their natural Dexterity.
Light Armor
Attempting to swim while wearing light armor requires that you make a DC 10 Strength (Athletics) check each round. Failure means you have a speed of 0 as you go under water for that round and loose one carried item, shield or weapon (your choice as to what you drop).
If you choose to remove your armor after entering the water, it will take one minute (10 rounds). A successful DC 15 Dexterity (Acrobatics) check will cut that time in half. During this time you cannot swim or take any other actions. You make a DC 10 Dexterity (Acrobatics) check each round. Each round that you succeed you keep your head above water and counts as one round of the rounds required to remove your armor. Failure means that you went under water this round and made no headway in removing your armor. After 3 failures you receive one level of exhaustion.
Medium Armor
You can attempt to swim while wearing medium armor, but you must make DC 15 Strength (Athletics) check each round. On a success, if you are on the surface at the beginning of the round, you stay on the surface. Each foot you swim cost you two extra feet of speed and you can take no other actions besides shouting and stowing a weapon. A failed check means you sink 10 feet and lose any still-carried shields or weapons. On the round following a failed check you are under water. After that, on a successful check you can swim toward the surface at a rate of 15 feet per round. On failure you sink another 10 feet.
You can attempt to remove your armor, but you will be sinking at a rate of 10 feet per round during this time. It normally takes 1 minute (10 rounds) to doff your armor, but a successful DC 15 Dexterity (Acrobatics) check will cut that time in half. Without your armor you can swim toward the surface at a rate of 20 feet per round.
Heavy Armor
You cannot swim while wearing heavy armor, giving you an effective speed of 0. Whenever you are in water, you lose any carried shields and weapons and begin to sink. You make a DC 25 Strength (Athletics) check each round. Success keeps your head above water, or if you start the round under water you can swim 15 feet toward the surface. You can take no other actions. A failed check means you sink another 20 feet.
You can attempt to remove your armor, but you will be sinking at a rate of 20 feet per round during this time. It normally takes 5 minutes (50 rounds) to doff your armor, but a successful DC 15 Dexterity (Acrobatics) check will cut that time in half. Without your armor you can swim toward the surface at a rate of 20 feet per round.
Drowning
After 1+(con bonus) minutes of holding your breath underwater you fall unconscious, your hit points fall to 0, and you can then survive for a number of rounds equal to your Constitution modifier (minimum 1 round). After that, you begin making your death saving throws as per the standard rules. However, if you become stable there is a problem. If you are still under water you can’t remain stable. So you must start making death saving throws again. This continues until you die unless you are saved in some way.
Dungeon Master Assistance 
I like the rules. That is all.
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Thanks.
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Pg 146 player’s handbook: it takes 1 minute to doff medium armor.
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Excellent catch!
I revised the post. Thank you very much. Now I need to go back and change that in my Ship-to-ship combat rules “Nautical Adventures”.
If you find any other errors in this or any other of my posts, please don’t hesitate to tell me.
Thanks again,
Ronny
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Reblogged this on dmleviathan.
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i had read somewhere that if you are caught by surprise that you cannot hold your breath in the same manner in which you were prepared to hold your breath so that instead of the 1+con modifier in minutes it becomes 1+ con modifier in rounds.
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That sounds like a reasonable house rule. Do you know where you read that?
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It should be in the DMG under “underwater adventuring” in the exploration segment, if memory serves.
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It isn’t in the DMG, but thank you for pushing me on this. As a result of my research I have edited my original post – In the drowning section I added “, and you can then survive for a number of rounds equal to your Constitution modifier (minimum 1 round).”
As far your original post regarding how surprise effects how long you can hold your breath, it doesn’t look like it is addressed in either the PHB or the DMG. I think I wall use a general house rule that whenever you are unable to prepare to hold your breath by taking in a lung full of air, your drop to 0 HP after a number of rounds equal to your Constitution modifier (minimum 1 round). Simply being surprised is not enough to prevent you from taking a breath.
Here is what it says in the PHB:
“A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum of 30 seconds). When a creature runs out of breath, it can survive for a number of rounds equal to its Constitution modifier (minimum 1 round). At the start of its next turn, it drops to 0 hit points and is dying.”
“For example, a creature with a Constitution of 14 can hold its breath for 3 minutes. If it starts suffocating, it has 2 rounds to reach air before it drops to 0 hit points”
With this added in the official Errata: “If you run out of breath or are choking, you can’t regain hit points or be stabilized until you can breathe again.”
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In regards to drowning. What if one is unconscious underwater? Do their hit points immediately fall to zero?
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No.
But exactly how to handle the situation will by up to the DM and will depend a lot on why they are unconscious.
Here is how I would do it.
I would let an unconscious character whose current hit point total was above 0 hold his breath for the same amount of time that I would if he was conscious. If he was unconscious as the result of a sleep spell, for instance, it reads in part that the target “falls unconscious until the spell ends, the sleeper takes damage, or someone uses an action to shake or slap the sleeper awake.” I believe that it is in the spirit of the rules that this would also apply to any level of violence as slapped or shaken would do. I think that attempting to take a breath underwater would be enough of a shock to become conscious. This would also apply to most of the time when a character is asleep or unconscious for whatever reason.
If he is unconscious because of an Astral Projection spell, being underwater has no effect because the body he leaves behind doesn’t require air.
If he is unconscious because another character knocked him out, then he is already at 0 hit points, but stable. In that case or any time that he is unconscious at 0 HP and stable, if he is underwater he is no longer stable and will have to start making death saving throws as I said under “Drowning” in my original post.
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so just curious if you were to say start drowning in a pool of healing water as my dm stated it would you eventually die or would the water continue stabilizing you until such a time as it ran out since it is after all healing water like a health potion?
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That is quite a question. So can you drown in a pool of healing potion?
That would be up to the DM. I can see 3 different, and equally reasonable, options:
1) When you are holding your breath, your hit points don’t drop at all until you fall unconscious for lack of air. So, before you fall unconscious you could drink as much healing potion as you want but it would never increase your HP above your HP maximum. Your DM might rule that you wouldn’t be able to drink any after you were unconscious your hit points fall to 0. So yes you could drown.
2) It would be just as reasonable for your DM to rule that your character would begin to gulp the liquid he was submerged in while trying to breath even after going unconscious. (Similar to allowing another character to give an unconscious character a healing potion.) In this case then yes, he would survive and not be required to make saving throws. This would be true even if he didn’t realize that he was in a lake of healing potion and not a lake of water. If he knew that it was healing potion he could simply take a gulp before he passed out and continue doing this as long as he wanted to. Never mind that he doesn’t have any air in his lungs – this is magic!
3) What I would do.
If it was my game I might create a new rule just for this situation. Perhaps I would use drowning rules as presented in my original post, but the character would not lose any hit points and would not go unconscious. At the points where he would normally make death saves he would instead make constitution saves (1 per minute). Perhaps with a DC of 12 and with each failed save he would receive one point of exhaustion. This would reflect that healing potions (In my game) have their limits. Although they can heal you they can’t keep you alive forever without air.
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Players can now choose races that have swim speeds and even breath underwater,
Does their swim speed affect the wearing of armor?
How does mariners scale mail interact with the medium armor paragraph?
Can someone who breaths underwater wearing heavy armor, sink to the bottom and then walk around, effective speed = 1/2 normal walking speed due to difficult terrain, rather than speed=0
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Hi Derek. Great question.
Mariner’s Armor is a magical effect that is added to the armor. Everything else about the armor remains the same. The main thing that mariners armor gives you is a swim speed. I would rule that if your magic armor gives you a swim speed you can ignore all of my rules regarding the effects of wearing armor while in water except for these (which should be added):
1) If your character has a swim speed it is effected by the wearing of armor the same way your walking speed is. PHB p. 144 “If the armor table shows “Str 13” or “Str 15” in the Strength column for an armor type, the armor reduces the wearer’s speed by 10 feet unless the wearer has a strength score equal to or higher than the listed score.” In this case your swim speed will also be reduced by 10 feet when wearing this armor. Other armor (such as mariners scale mail) will not reduce your swim speed.
2) I would rule that if you are carrying at least 60 pounds (including your armor) You can walk on the bottom. This would be considered difficult terrain so you would move at half your walk speed.
3) Drowning rules do not apply if your character can breath under water.
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In a number of paragraphs you mention making ‘DC xx Strength (Athletics) saving throw’ do you actually mean ‘DC xx Athletics check’ or ‘DC xx Strength saving throw’ our DM was confused as to which you mean and it can make a difference with abilities which affect Athletics?
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I apologize for the confusion. In most cases there is little difference in a check and a save, but I was sloppy in my descriptions. They should all read “Strength (Athletics) check”.
If you re-read the post now, you will see that I have corrected it. Thank you for pointing out my mistake.
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Beautiful post, will be implementing these drowning rules at my table next session.
Thank you
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Thanks.
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My DM found these rules while looking for rules that govern wearing heavy armor in water and used them
Our fighter was wearing platemail and we got teleported into the middle an ocean
He died in a fit of panicked terror desperately trying to doff his armor
As our party’s barbarian I give it a 10/10
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I doubt if the fighter would rate it quite so high! 🙂
He must have failed several strength checks. I don’t know what the DM had in mind, but (if I had been the DM) I think that if the others in the group had all helped him, me might have survived.
First he needed to get his head above water. I would have allowed him advantage on his rolls if another character was helping him. If more than one was helping him, I would have allowed you to hold his head above water while he – with others help – removed his armor. He may have still drowned, but he would have had a better chance.
Now if everyone in the party was wearing heavy armor, I could only hope they were all very strong or very lucky!
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The losing all carried items seems a bit harsh. I feel like you should be able to hold on to them with some added penalty, like minus 1 or 2 on the ability check to keep floating instead.
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I agree. I’ve been giving the players a choice – either drop anything you are carrying in your hands, or sink 10 feet his round while you store those items, or make your Strength (Athletics) check with a -2 penalty.
Note that this only applies to things you are carrying in your hands and does not apply to things like your backpack or stowed items. It also does not apply to your shield if you are using one. A shield is assumed to be strapped to you arm.
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