Environment

By its nature, adventuring involves delving into places that are dark, dangerous, and full of mysteries to be explored. The rules in thissection cover some of the most important ways in which adventurersinteract with the environment in such places.

Falling

A fall from a great height is one of the most common hazards facing anadventurer. At the end of a fall, a creature takes 1d6 bludgeoningdamage for every 10 feet it fell, to a maximum of 20d6. The creaturelands prone, unless it avoids taking damage from the fall.

Suffocating

A creature can hold its breath for a number of minutes equal to 1 + itsConstitution modifier (minimum of 30 seconds). When a creature runs out of breath or is choking, it can survive for anumber of rounds equal to its Constitution modifier (minimum of 1round). At the start of its next turn, it drops to 0 hit points and isdying, and it can't regain hit points or be stabilized until it canbreathe again. For example, a creature with a Constitution of 14 can hold its breathfor 3 minutes. If it starts suffocating, it has 2 rounds to reach airbefore it drops to 0 hit points.

Vision and Light

The most fundamental tasks of adventuring---noticing danger, findinghidden objects, hitting an enemy in combat, and targeting a spell, toname just a few---rely heavily on a character's ability to see. Darknessand other effects that obscure vision can prove a significant hindrance. A given area might be lightly or heavily obscured. In a lightly obscured area, such as dim light, patchy fog, or moderate foliage,creatures have disadvantage on Wisdom (Perception) checks that rely onsight. A heavily obscured area---such as darkness, opaque fog, or densefoliage---blocks vision entirely. A creature effectively suffers fromthe blinded condition when trying to see something in that area. The presence or absence of light in an environment creates threecategories of illumination: bright light, dim light, and darkness. Bright light lets most creatures see normally. Even gloomy daysprovide bright light, as do torches, lanterns, fires, and other sourcesof illumination within a specific radius. Dim light, also called shadows, creates a lightly obscured area. Anarea of dim light is usually a boundary between a source of brightlight, such as a torch, and surrounding darkness. The soft light oftwilight and dawn also counts as dim light. A particularly brilliantfull moon might bathe the land in dim light. Darkness creates a heavily obscured area. Characters face darknessoutdoors at night (even most moonlit nights), within the confines of anunlit dungeon or a subterranean vault, or in an area of magicaldarkness.

Blindsight

A creature with blindsight can perceive its surroundings without relyingon sight, within a specific radius. Creatures without eyes, such asoozes, and creatures with echolocation or heightened senses, such asbats and true dragons, have this sense.

Darkvision

Many creatures in fantasy gaming worlds, especially those that dwellunderground, have darkvision. Within a specified range, a creature withdarkvision can see in darkness as if the darkness were dim light, soareas of darkness are only lightly obscured as far as that creature isconcerned. However, the creature can't discern color in darkness, onlyshades of gray.

Truesight

A creature with truesight can, out to a specific range, see in normaland magical darkness, see invisible creatures and objects,automatically detect visual illusions and succeed on saving throwsagainst them, and perceives the original form of a shapechanger or acreature that is transformed by magic. Furthermore, the creature can seeinto the Ethereal Plane.

Food and Water

Characters who don't eat or drink suffer the effects of exhaustion. Exhaustion caused by lack of food or water can't beremoved until the character eats and drinks the full required amount.

Food

A character needs one pound of food per day and can make food lastlonger by subsisting on half rations. Eating half a pound of food in aday counts as half a day without food. A character can go without food for a number of days equal to 3 + his orher Constitution modifier (minimum 1). At the end of each day beyondthat limit, a character automatically suffers one level of exhaustion. A normal day of eating resets the count of days without food to zero.

Water

A character needs one gallon of water per day, or two gallons per day ifthe weather is hot. A character who drinks only half that much watermust succeed on a DC 15 Constitution saving throw or suffer one level of exhaustion at the end of the day. A character with access to evenless water automatically suffers one level of exhaustion at the end of the day. If the character already has one or more levels of exhaustion, the character takes two levels in either case.

Interacting with Objects

A character's interaction with objects in an environment is often simpleto resolve in the game. The player tells the GM that his or hercharacter is doing something, such as moving a lever, and the GM describes what, if anything, happens. For example, a character might decide to pull a lever, which might, inturn, raise a portcullis, cause a room to flood with water, or open asecret door in a nearby wall. If the lever is rusted in position,though, a character might need to force it. In such a situation, the GM might call for a Strength check to see whether the character can wrenchthe lever into place. The GM sets the DC for any such check based on thedifficulty of the task. Characters can also damage objects with their weapons and spells. Objects are immune to poison and psychic damage, but otherwise they canbe affected by physical and magical attacks much like creatures can. TheGM determines an object's Armor Class and hit points, and might decidethat certain objects have resistance or immunity to certain kinds ofattacks. (It's hard to cut a rope with a club, for example.) Objectsalways fail Strength and Dexterity saving throws, and they are immune toeffects that require other saves. When an object drops to 0 hit points,it breaks. A character can also attempt a Strength check to break an object. The GM sets the DC for any such check.