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Someone under the water has total cover from someone on the land. If you are in the water but not under it you have partial cover from a land based opponent. What I'd like to know is if you are in the water (but not under it) and want to attack someone underneath the water, do they have cover and is it total or partial?

Azeari
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jsecker
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1 Answers1

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Yes.

From the DMG 3.5, page 93:

Characters swimming, floating, or treading water on the surface, or wading in water at least chest deep, have improved cover (+8 bonus to AC, +4 bonus on Reflex saves) from opponents on land. Landbound opponents who have freedom of movement effects ignore this cover when making melee attacks against targets in the water. A completely submerged creature has total cover against opponents on land unless those opponents have freedom of movement effects.

(the same rule in the Pathfinder Reference Document)

My own interpretation of this rule is as follows:

If you are attacking with a weapon and you aren't subject to freedom of movement, then the surface of the water blocks line of effect. This means that two creatures who are at least chest deep in water have improved cover relative to each other. A creature who is completely submerged has total cover and therefore cannot be attacked.

PHB 3.5, page 152:

If you don’t have line of effect to your target he is considered to have total cover from you. You can’t make an attack against a target that has total cover.

Azeari
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  • That being said, I would love to know where they got this rule from. I was surprised to find that it is the same in Pathfinder as in vanilla 3.5 – Azeari Jan 26 '11 at 04:07
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    Why does the surface of a liquid act like a wall of force against weapon attacks? Surely this makes the harpoon a pointless weapon.

    IMHO, water should grant a nonmagical displacement effect: "The creature benefits from a 50% miss chance as if it had total concealment. However, unlike actual total concealment, displacement does not prevent enemies from targeting the creature normally."

    This is how spear fishermen catch their meal: they train themselves to adjust their aim to account for the refractivity of water, so that they spear the fish instead of stabbing themselves in the leg.

     – Azeari Jan 26 '11 at 04:17
  • There is a feat called "Aquatic Spellcasting" in "Lords of Madness", which allows a land based creature to ignore the 'line of effect' rule in the case of water. I would consider that if any land based creature wants to attack someone under the water, using a spear, they would need a similar feat. I would be careful about adjusting the rules to make it more sensible to you, since there are creatures whose tactics rely upon total cover provided by water. – jaye1234 Jan 26 '11 at 05:30
  • That feat only relates to spells, not to weapon attacks, which the question is about. In any case, none of my players have taken that feat, so it is not an issue for my own game. – Azeari Jan 26 '11 at 06:14
  • @Azeari : You could always ask your players to take "Vow of Poverty", that will give them "Freedom of Movement" as an extraordinary ability at level 14. But the way I see it, this is just one of the many small rules that don't make sense if it is the real world. – jaye1234 Jan 26 '11 at 09:07
  • I would not rule that line of effect is blocked - that requires total cover, not improved cover. Note the definition of line of effect (http://www.d20pfsrd.com/magic#TOC-Line-of-Effect) and the definition of improved cover (http://www.d20pfsrd.com/gamemastering/combat#TOC-Cover) - basically an arrow slit is improved cover but doesn't block line of effect. Water would be the same. – mxyzplk Jan 28 '11 at 01:42
  • @mxyzplk You only have line of effect to the parts of the person that are above water. Essentially, the surface of the water is treated as a "solid barrier" in these circumstances. That is why they have a cover bonus to AC when they are partially submerged. – Azeari Jan 28 '11 at 02:21
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    @Azeari not correct. At least in Pathfinder, under Attacks from Land, "Magical effects are unaffected except for those that require attack rolls (which are treated like any other effects) and fire effects." http://www.d20pfsrd.com/gamemastering/environment/wilderness#TOC-Underwater-Combat One of many improvements in 3.x brought to you by Pathfinder! – mxyzplk Jan 28 '11 at 03:22
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    That rule seems to be dealing with melee attacks only; as GM I would allow an archer/harpoonist to shoot/throw at a fully submerged target, with some sort of penalty. – jeffszusz Jan 29 '11 at 06:26
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    @Azeari - have you ever tried to throw a spear into water? If you're trying to emulate a realistic environment, you'll have the surface of the water slow down projectiles, change their trajectory, and cause underwater objects to appear displaced from their actual position. – blueberryfields Jan 31 '11 at 02:23
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    I think people's version on what is realistic to happen with water may come from what they see on movies, tv, etc. Mythbusters (yes I do realize is a tv show), showed that it only takes a very small amount of water to stop a bullet fired from a high powered rifle. http://kwc.org/mythbusters/2005/07/mythbusters_bulletproof_water.html – jaye1234 Jan 31 '11 at 03:09
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    @blueberryfields I agree that nonmagical displacement (50% miss chance) would be a much better mechanic than total cover, in this situation. In 3.5, ranged weapons are -2 to hit for each 5ft of water the ammunition passes through – Azeari Jan 31 '11 at 06:36
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    @jaye1234 the guns that they tested were all supersonic (> 1,126 ft/s muzzle velocity), which is probably why the bullets disintegrated on impact with the surface of the water. At that speed, treating it as a brick wall is not at all unrealistic! – Azeari Jan 31 '11 at 06:38