D&D 5E Swimming, Breathing, and Drowning... (ruling question)

[NotAYakk]

Real life world records are 24 minutes for just holding breath, and about 2 minutes for a underwater "sprint" swim (distance record).

I would posit that a 20 con PC should be able to match or exceed those feats.

The base rules put 20 con at 5 minutes. If you halve that time for "combat level" effort, and x5 that time for "do nothing but hold breath", it roughly matches the real world record performances.

For do nothing but hold breath, I'd allow (athletics proficiency) multiplier on duration. That lets high level expertise be superhuman slightly.

For normal action, take the base rules (con mod minutes), after which you have to make a con save with DC equal to the number of rounds since you ran out of breath at the end of your turn.

Strenuous activity (combat, dashing, similar) doubles the rate you run out of breath, and increases the DC by 2 per round when out of breath, and makes your save for that turn be at disadvantage.

Taking damage requires a concentration save or you fail to hold your breath. When out of breath, failing this concentration check makes you swallow water and become incapacitated.

 

[LordEntrails]

Hope that they took Silent spell?

I mean, exactly how useful is a fighter in an aerial battle if they don’t have wings or flight magic? Why do we have to be inclusive for spellcasters if they are in an environment that’s natively hostile to them?

No one is any good at aerial battles except those races that can fly. Do you mean ranged combat? Every class can do something with ranged combat.

If you're PLANNING on an underwater fight, then you should invest in potions of water breathing, or a cloak of the manta ray, or something similar. But when you're just trying to travel downriver, and your rowboat gets capsized by a troupe of sahuagin and your mage gets dragged under, you'd best be able to quickly balance the risk/reward equation of casting a spell.

When I said "you", I meant the DM, not the characters.

Real life world records are 24 minutes for just holding breath, and about 2 minutes for a underwater "sprint" swim (distance record).

I would posit that a 20 con PC should be able to match or exceed those feats.

I would not equate the two. Maybe a 20 Con with appropriate feats. Most swimmers can hold their breath for a few minutes without specific training. But, in general you are right and IMO it's not worth quibbling over RAW.