Environment

Primarily used during exploration, environment rules bring the locales your party travels through to life. You’ll often be able to use common sense to adjudicate how environments work, but you’ll need special rules for environments that really stand out.

Each of the environments presented in this section uses the terrain rules (which are summarized on page 514 and appear in full beginning on page 475) in different ways, so be sure to familiarize yourself with those rules before reading this section. Some environments refer to the rules for climate (page 517) and natural disasters (beginning on page 517). Many places have the traits of multiple environments; a snow-covered mountain might use both the arctic and mountain environments, for example. For environmental features with effects based on how tall or deep they are, those effects vary further based on a creature’s size. For instance, a shallow bog for a Medium creature might be a deep bog for smaller creatures, and a deep bog for a Medium creature could be only a shallow bog for a larger creature (and so insignificant for a truly massive creature that it isn’t even difficult terrain).

Table 10–12 lists the features of various environments alphabetically for quick reference. The Proficiency DC Band entry indicates a range of appropriate simple DCs for that environmental feature, while also providing a rough estimate of the danger or complexity of the feature.

Environmental Damage

Some environmental features or natural disasters deal damage. Because the amount of damage can vary based on the specific circumstances, the rules for specific environments and natural disasters use damage categories to describe the damage, rather than exact numbers. Use Table 10–11 below to determine damage from an environment or natural disaster. When deciding the exact damage amount, use your best judgment based on how extreme you deem the danger to be.

Table 10–11: Environmental Damage

Category	Damage
Minor	1d6–2d6
Moderate	4d6–6d6
Major	8d6–12d6
Massive	18d6–24d6

Aquatic

Aquatic environments are among the most challenging for PCs short of other worlds and unusual planes. PCs in an aquatic environment need a way to breathe (typically a water breathing spell) and must usually Swim to move, though a PC who sinks to the bottom can walk awkwardly, using the rules for greater difficult terrain. Characters in aquatic environments make frequent use of the aquatic combat (page 478) and drowning and suffocation rules (page 478).

Currents and Flowing Water

Ocean currents, flowing rivers, and similar moving water are difficult terrain or greater difficult terrain (depending on the speed of the water) for a creature Swimming against the current. At the end of a creature’s turn, it moves a certain distance depending on the current’s speed. For instance, a 10-foot current moves a creature 10 feet in the current’s direction at the end of that creature’s turn.

Visibility

It’s much harder to see things at a distance underwater than it is on land, and it’s particularly difficult if the water is murky or full of particles. In pure water, the maximum visual range is roughly 240 feet to see a small object, and in murky water, visibility can be reduced to only 10 feet or even less.

Arctic

The main challenge in an arctic environment is the low temperature, but arctic environments also contain ice and snow. The disasters that most often strike in arctic environments are avalanches, blizzards, and floods.

Ice

Icy ground is both uneven ground and difficult terrain, as characters slip and slide due to poor traction.

Snow

Depending on the depth of snow and its composition, most snowy ground is either difficult terrain or greater difficult terrain. In denser snow, characters can attempt to walk along the surface without breaking through, but some patches might be loose or soft enough that they’re uneven ground.

Desert

Desert encompasses sandy and rocky deserts as well as badlands. Though tundra is technically a desert, it’s classified as arctic, as the climate is the primary challenge in such areas. Sandy deserts often have quicksand hazards (page 526) and sandstorms.

Rubble

Rocky deserts are strewn with rubble, which is difficult terrain. Rubble dense enough to be walked over rather than navigated through is uneven ground.

Sand

Packed sand doesn’t usually significantly impede a character’s movement, but loose sand is either difficult terrain (if it’s shallow) or uneven ground (if it’s deep). The wind in a desert often shifts sand into dunes, hills of loose sand with uneven ground facing the wind and steeper inclines away from the wind.

Forest

These diverse environments include jungles and other wooded areas. They are sometimes struck by wildfires.

Canopies

Particularly dense forests, such as rain forests, have a canopy level above the ground. A creature trying to reach the canopy or travel along it must Climb. Swinging on vines and branches usually requires an Acrobatics or Athletics check. A canopy provides cover, and a thicker one can prevent creatures in the canopy from seeing those on the ground, and vice versa.

Trees

While trees are omnipresent in a forest, they typically don’t provide cover unless a character uses the Take Cover action. Only larger trees that take up an entire 5-foot square on the map (or more) are big enough to provide cover automatically.

Undergrowth

Light undergrowth is difficult terrain that allows a character to Take Cover. Heavy undergrowth is greater difficult terrain that automatically provides cover. Some sorts of undergrowth, such as thorns, might also be hazardous terrain, and areas with plenty of twisting roots might be uneven ground.

Plains

The plains environment encompasses grasslands such as savannas and farmland. The most common disasters in plains are tornadoes and wildfires.

Hedges

Hedges are planted rows of bushes, shrubs, and trees. Their iconic appearance in adventures consists of tall hedges grown into mazes. A typical hedge is 2 to 5 feet tall, takes up a row of squares, and provides cover. A character trying to push through a hedge faces greater difficult terrain; it’s sometimes faster to Climb over.

Undergrowth

Light undergrowth is difficult terrain that allows a character to Take Cover. Heavy undergrowth is greater difficult terrain that provides cover automatically. Undergrowth in plains is usually light with a few scattered areas of heavy undergrowth, but fields of certain crops, like corn, are entirely heavy undergrowth.

Swamp

Wetlands are the most common kind of swamp, but this category also includes drier marshes such as moors. Swamps often contain quicksand hazards (page 526). Despite their soggy nature, swamps aren’t very likely to experience heavy flooding, since they act as natural sponges and absorb a great deal of water before they flood.

Bogs

Also called mires, bogs are watery areas that accumulate peat, are covered by shrubs and moss, and sometimes feature floating islands of vegetation covering deeper pools. Shallow bogs are difficult terrain for a Medium creature, and deep bogs are greater difficult terrain. If a bog is deep enough that a creature can’t reach the bottom, the creature has to Swim. Bogs are also acidic, so particularly extreme or magical bogs can be hazardous terrain.

Undergrowth

Light undergrowth is difficult terrain that allows a character to Take Cover, while heavy undergrowth is greater difficult terrain that provides cover automatically. Some sorts of undergrowth, such as thorns, are also hazardous terrain, and areas with plenty of twisting roots are uneven ground.

Underground

Underground environments consist of caves and natural underground areas. Artificial dungeons and ruins combine underground features with urban features like stairs and walls. Deep underground vaults have some of the same terrain features as mountains, such as chasms and cliffs. The most common disasters underground are collapses.

Floors

Natural underground environments rarely have flat floors, instead featuring abrupt changes in elevation that result in difficult terrain, uneven ground, and inclines.

Ledges

Ledges are narrow surfaces that overlook a lower area or provide the only means to move along the edge of a chasm. Moving across a narrow ledge requires using

Acrobatics to Balance.

Rubble

Caverns can be covered in rubble, which is

difficult terrain. Deep or pervasive rubble is

also uneven ground.

Stalagmites and Stalactites

Stalagmites are tapering columns that rise from the floor of a cave. Areas

filled with stalagmites are greater

difficult terrain, and especially large

stalagmites have to be sidestepped

or Climbed. Stalagmites can be sharp enough they can be used as hazardous terrain in some circumstances, as can stalactites (icicle-shaped formations that hang from the roof of a cave) if they’re knocked loose from a ceiling or overhang.

Walls

Natural cave walls are uneven, with nooks, crannies, and ledges. Since most caves are formed by water, cave walls are often damp, making them even more difficult to Climb.