In Pathfinder, How far does one sink after failing a swim check?

Can't seem to find any ruling on it. Do they sink deeper? If so is it based on how much they fail the swim check by? Or set amounts like 5,10,15 feet per fail? Or just Float just under the surface?

I know you move at 1/2 your speed as a fullround action. So to me, most characters move 15feet on a success, so failing wouldn't make sense to sink at the same speed of a character purposely swimming a certain direction in the same 6 seconds. Logically anyways. Perhaps encumberance / weight / materials of items worn effect buoyancy? (Seems like that would over complicate things though)

Anyone know if there is a certain Pathfinder ruling/book that expands on this? Or is it left completely up to the DM? Thanks!


3 Answers 3


They sink for 10 feet on the first round

The Aquatic Adventures campaign setting clarifies how this works (page 43):

Buoyancy Speed: A creature begins to sink or rise at the end of its turn the first time it badly fails (or does not attempt) a Swim check, moving up or down as appropriate at a speed of 10 feet; this speed increases by 10 feet each subsequent round unless the creature is stopped, to a maximum speed of 30 feet after 3 rounds. This movement provokes attacks of opportunity as normal. While sinking or rising because of its buoyancy, creatures are considered off-balance (see Off-Balance and Prone Underwater on page 45). Once per round, a creature sinking or rising because of its buoyancy can stop its momentum by succeeding at a Swim check as a move action.

A creature that chooses to continue moving in the direction of its buoyancy under its own power, rather than through uncontrolled rising or sinking, can do so with a successful Swim check without needing to stop first. If a creature’s buoyancy changes instantly while sinking or rising from buoyancy (such as via jettisoning something it’s holding or using magic), its buoyancy speed adjusts by 10 feet in the new direction each round. A creature that fails the DC 20 Swim check to move against its buoyancy while swiftly sinking or swiftly rising moves 30 feet in the appropriate direction immediately.

So, at the moment you fail your Swim skill check, you go underwater and begin sinking. Initially, you sink only 10 feet, but each consecutive round that you do not stop this movement (using a move action and a Swim check), you will move an additional 10 feet, for another of 20 feet on the second round (total 30 feet) and 30 feet on the third round (total 60 feet).

This answer explains exactly how Buyoancy works:

Basically buyoancy makes a creature go up or down when swimming. Whenever they fail a DC check by 5 or more, or when they do not spend any actions to swim, the creature either rises or sinks due to buoyancy. It has three normal states: sinking, rising and neutral.

Land creatures usually have a sinking buoyancy, unless they are carrying a substantial amount of low-density gear (like many wooden items) and little or no high-density gear (items made of metal or stone). The book presents air tanks and gear that can change your buoyancy on demand.

Buoyancy also has two extreme states: swiftly sinking and swiftly raising. If they are swiftly sinking, their carried gear is so dense that they can walk at the bottom of the body of water, and must make a DC 20 check to stay off the bottom. If they are swiftly raising, they must make a DC 20 Swim check to stay submerged, or they will move to the surface of the body of water.

The speed of this buoyancy-based movement depends on your Swim checks. Whenever you fail (or do not make) a Swim check, you move up or down 10 feet, and every turn after the first that you do not attempt to fix that, the speed increases by another 10 feet to a maximum of 30 feet per round after 3 rounds. When swiftly sinking or swiftly rising, a failure means you immediately move 30 feet in that direction. Also, while moving like this, the creature is considered off-balance.

When moving against your buoyancy, your movement is hindered, much like a flying creature flying upwards. As such, each 5 feet of movement in the opposite direction of your buoyancy costs you 10 feet of your movement.


A swim check states:

Check: Make a Swim check once per round while you are in the water. Success means you may swim at up to half your speed (as a full-round action) or at a quarter of your speed (as a move action). If you fail by 4 or less, you make no progress. If you fail by 5 or more, you go underwater.

You only just go under the water, you don't sink. Imagine a large wave crashing over someone and them floundering under the water for a few seconds before coming back to the surface, that's a failed swim check. Obviously they only come back to the surface when they pass a swim check.

Someone would only sink if they were either unconscious or if they had a heavy load (although there are no rules on it as a house rule I add +10dc for medium encumbrance and automatic sink for heavy encumbrance).

Now as for how fast they would sink, this would depend on a lot of factors, such as the persons body mass, what they are wearing, total weight etc. So the average swimmer with no equipment carried and lungs full of air won't sink, they'll float. But if they're unconscious and have expelled most of that air, they may well sink but it wouldn't be very quickly. 5' a round seems about right. You will simply have to make a judgement call on a case by case basis.

  • \$\begingroup\$ Medium and heavy encumberance apply “armor” check penalties, which apply to Swim checks. \$\endgroup\$
    – KRyan
    Feb 24, 2014 at 1:56
  • \$\begingroup\$ So sinking from failed swim saves is not a rulebook rule, it would be more of a house rule then. It would be more RAW to just struggle under the surface of the water until you pass your swim check successfully. Then any sinking added then on would just be up to the DM's discretion? \$\endgroup\$
    – Jeff
    Feb 24, 2014 at 2:04
  • \$\begingroup\$ @kryan can you point me to where that's in the rules please? Under skills the acp says it may be affected by encumbrance, but I've not seen an actual rule for it. \$\endgroup\$
    – Styphon
    Feb 24, 2014 at 7:11
  • \$\begingroup\$ @jeff failing a swim check isn't meant to hurt the characters too badly. They can hold their breath underwater for CON rounds. The rules do say if doing anything more than a standard action remove one round from that, so you could house rule that as they weren't expecting to go under, and as they are struggling to get back to the surface, they only have half CON rounds until they start drowning. It's at that point you could say they start sinking if you like, or if they keep failing swim checks, for dramatic tension each failed check could have them slip under a little deeper. \$\endgroup\$
    – Styphon
    Feb 24, 2014 at 7:13
  • \$\begingroup\$ @Styphon Table: Encumbrance Effects, with all the other encumbrance rules. \$\endgroup\$
    – KRyan
    Feb 24, 2014 at 12:50

After failing a swim check by five or more, sinking is at the GM's discretion. Once you're underwater, drowning becomes a concern. You can keep trying to make swim checks which, if you pass, means you can take full-round or move actions to head back to the surface for a breath of air.


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