The adventuring world is filled with dangers beyond dragons and ravening fiends. Hazards are location-based threats that have much in common with traps, but are usually intrinsic to their area rather than constructed.
Hazards fall into three main categories: environmental, living, and magical.
Environmental hazards include subterranean threats like cave-ins and wilderness dangers like forest fires.
Living hazards are creatures that are generally too passive to be considered monsters, but are still a threat to unwary adventurers, such as dangerous molds, slimes, and fungi.
Magical hazards are the most unpredictable, and can be the legacy of arcane experimentation, strange underground radiations, or ancient enchantments gone awry.
Hazards have challenge ratings like traps or monsters. A typical hazard triggers if a creature ventures near or into it, causing hit point damage, ability damage or drain, or some other harmful effect. Most can be detected by wary and knowledgeable PCs. Every hazard should have a means of escape or a way to eliminate the hazard, if not both.
Presented below are a variety of unusual hazards.