The Environment
===============

By its nature, adventuring involves delving into places
that are dark, dangerous, and full of mysteries to be
explored. The rules in this section cover some of the
most important ways in which adventurers interact with
the environment in such places. The Dungeon Master’s
Guide has rules covering more unusual situations.

Falling
-------

A fall from a great height is one of the most common
hazards facing an adventurer.

At the end of a fall, a creature takes 1d6 bludgeoning
damage for every 10 feet it fell, to a maximum of 20d6.
The creature lands prone, unless it avoids taking
damage from the fall.


Suffocating
-----------

A creature can hold its breath for a number of minutes
equal to 1 + its Constitution modifier (minimum
of 30 seconds).

When a creature runs out of breath, it can survive for
a number of rounds equal to its Constitution modifier
(minimum 1 round). At the start of its next turn, it drops
to 0 hit points and is dying.

For example, a creature with a Constitution of 14 can
hold its breath for 3 minutes. If it starts suffocating, it
has 2 rounds to reach air before it drops to 0 hit points.


Vision and Light
----------------

The most fundamental tasks of adventuring—noticing
danger, finding hidden objects, hitting an enemy in
combat, and targeting a spell, to name just a few—
rely heavily on a character’s ability to see. Darkness
and 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 on sight.

A **heavily obscured** area-such as darkness, opaque
fog, or dense foliage-blocks Vision entirely. A creature
in a heavily obscured area effectively suffers from the
blinded condition (see appendix A).

The presence or absence of light in an environment
creates three categories of illumination: bright light, dim
light, and darkness.

**Bright light** lets most creatures see normally. Even
gloomy days provide bright light, as do torches, lanterns,
fires, and other sources of illumination within a
specific radius.

**Dim light**, also called shadows, creates a lightly
obscured area. An area of dim light is usually a
boundary between a source of bright light, such as
a torch, and surrounding darkness. The soft light
of twilight ancl dawn also counts as dim light. A
particularly brilliant full moon might bathe the land
in dim light.

**Darkness** creates a heavily obscured area. Characters
face darkness outdoors at night (even most moonlit
nights), within the confines of an unlit dungeon or a
subterranean vault, or in an area of magical darkness.

Blindsight
^^^^^^^^^^

A creature with blindsight can perceive its surroundings
without relying on sight, within a specific radius.
Creatures without eyes, such as oozes, and creatures
with echolocation or heightened senses, such as bats
and true dragons, have this sense.

Darkvision
^^^^^^^^^^

Many creatures in the worlds of D&D, especially those
that dwell underground, have darkvision. Within a
specified range, a creature with darkvision can see in
darkness as if the darkness were dim light, so areas
of darkness are only lightly obscured as far as that
creature is concerned. However, the creature can’t
discern color in darkness, only shades of gray.

Truesight
^^^^^^^^^

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

Food and Water
--------------

Characters who don’t eat or drink suffer the effects of
exhaustion (see appendix A). Exhaustion caused by lack
of food or water can’t be removed until the character
eats and drinks the full required amount.

Food
^^^^

A character needs one pound of food per day and can
make food last longer by subsisting on half rations.
Eating half a pound of food in a day counts as half a day
without food.

A character can go without food for a number of days
equal to 3 + his or her Constitution modifier (minimum
1). At the end of each day beyond that 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 if the weather is hot. A character who
drinks only half that much water must 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 even less 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 simple to resolve in the game. The player tells
the DM that his or her character is doing something,
such a moving a lever, and the DM describes what, if
anything happens.

For example, a character might decide to pull a lever,
which might, in turn, raise a portcullis, cause a room to
flood With water, or open a secret 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 DM might
call for a Strength check to see whether the character
can wrench the lever into place. The DM sets the DC for
any such check based on the difficulty of the task.

Characters can also damage objects with their
weapons and spells. Objects are immune to poison and
psychic damage, but otherwise they can be affected
by physical and magical attacks much like creatures
can. The DM determines an object’s Armor Class and
hit points, and might decide that certain objects have
resistance or immunity to certain kinds of attacks. (It's
hard to cut a rope with a club, for example.) Objects
always fail Strength and Dexterity saving throws, and
they are immune to effects 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 DM sets the DC for any such check.