On the go? Listen to the audio version of the article here:

While playing D&D, have you ever wanted to explore underwater ruins but were worried about the possibility of drowning? I’ve got explanations for how drowning works in 5e and how to avoid it. But first, the basics of drowning according to the Player’s Handbook (pg. 183): 

You can hold your breath (1 + CON mod) minutes, min of 30sec (PHB pg 183). After, you have a number of rounds (6 sec each) equal to CON mod, min of 1. Then, drop to 0hp, dying. You cannot regain hp or stabilize until you can breathe again. Encumbrance doesn’t matter, except for affecting move speed.

Now, if you’re looking for more tips in surviving your underwater adventures, read on! 

Ways to prevent drowning 

Assuming you don’t have access to Water Breathing, and you’re planning on spending plenty of time beneath the waves, here are some ways to prevent drowning: 

How to Transforming Yourself into an Aquatic Animal 

Polymorph or Wild Shape yourself into a water-breathing creature is the easiest way to prevent drowning. However, bear in mind that Polymorph gives you the intelligence of the animal you change into, so it’s best to pick something more intelligent, such as a giant octopus. 

For options on underwater Polymorph and their intelligence. For intelligence, octopi are hard to beat. Here’s a table:

Alter Self also works if you want to roughly maintain your current form. Technically, you’d then temporarily be an aquatic animal.

Can You Make Air Bubbles?

If you have Shape Water or Control Water, you can generate a cube of water—filled with air— and stay within that air pocket for as long as the air or spell lasts, which is 1 hour for Shape Water, and 10 minutes for Control Water. 

Shape Water is clearly the better option, though; it’s a cantrip, it lasts an hour, and it can make you an air pocket that’s just under a 5ft cube in volume. According to this thread, that would lead to roughly 20min of breathing time. This is subject to DM agreement, of course.

If you’re wondering if you can cast spells underwater: yes, you can! Contrary to popular belief, being underwater does not stop you from casting spells. It’s even been confirmed in a Tweet by Jeremy Crawford, the lead rules designer for 5e.

Though some homebrew rules argue that, since Silence effectively blocks spells, then you need to have the ability to force air through your vocal chords. As such, these DMs say that you can cast only one spell underwater before running out of the air in your lungs.

Can Spells Stop You From Drowning?

Spells, like Rope Trick, can generate portals to other places which contain air and can hold 8 medium creatures. Other spells like Magnificent Mansion can work as a substitute. Again, there’s also Water Breathing and Alter Self.

For Genie Warlocks, you can also use your Genie’s Vessel at level 1 to take a break (once per long rest), and at level 10, you can bring your entire party in there (you plus 5 willing creatures)

Magical Items

Fortunately for non-casting classes, there are plenty of magical items that can aid with breathing underwater. Cloak of the Manta Ray, Cap of Water Breathing, and Necklace of Adaptation can confer water breathing as long as you are attuned to and wear them. If you’re unable to find these items, 100 gold coins can snag you a Potion of Water Breathing which lasts for an hour. 

Though a Bag of Holding sounds like a neat way to bring oxygen underwater, it’s not the most reliable method. Keep in mind that when opened, water will begin to rush in—unless you hold it upside down. 

You could bring someone in the Bag of Holding during your underwater adventures—but keep in mind they can only stay in there for 10 minutes (split among the number of creatures) before they begin to suffocate.

The Bag of Holding is probably a decent fix for sticking your head into the bag, catching your breath, and continuing to dive. No one says you need a constant supply of oxygen!

Summary

• According to the Player’s Handbook (pg. 183):
  • You can hold your breath (1 + Constitution modifier) minutes, minimum of 30sec. 
  • After running out of air, you have a number of rounds (6 sec each) equal to your Constitution modifier, with the minimum being 1 round. 
  • After the previous step, drop to 0 hp. You are dying and cannot regain hp or stabilize until you can breathe again.
• Spells can help with this, such as:
  • Water Breathing
  • Alter Self
  • Polymorph
  • Shape Water
  • Control Water
  • Rope Trick
  • Magnificent Mansion
• Two Class Features may help:
  • Wild Shape (Druids)
  • Genie Vessel (Genie Warlocks (TCE, pg 73)
• And a few Magical Items can come in handy, too:
  • Potion of Water Breathing
  • Cloak of the Manta Ray
  • Cap of Water Breathing
  • Necklace of Adaptation
  • Bag of Holding

There are plenty of options for surviving underwater and many routes to get there. My favorite is Shape Water, but some DMs may not like that route. The main question: what is most workable for you and your team, and what fits most with your character. 

Hope you found this helpful, and happy rolling!