Hill And Mountain Terrain

Usually formed by natural geological processes, chasms are common dangers in mountainous areas. Chasms aren’t hidden, so characters won’t (usually) fall into them by accident. A typical chasm is 2d4×10 feet deep, at least 20 feet long, and anywhere from 5 to 20 feet wide. It usually requires a successful DC 15 Athletics check to climb the wall of a chasm. In mountain terrain, chasms are typically 2d8×10 feet deep.

A vertical plane of stone, a rock wall requires one or more successful DC 25 Athletics checks to ascend. A typical rock wall is from 2d4×10 feet tall to 2d8×10 feet tall.

At particularly high altitudes, the thinning atmosphere poses a challenge for many creatures, with the same effects as a thin atmosphere (see page 396). A creature residing at a high altitude for 1 month becomes acclimated and no longer takes these penalties, but it loses this benefit if it spends more than 2 months away from high-altitude terrain and must reacclimatize upon returning.

As a guideline, the maximum distance in mountain terrain at which a creature can succeed at a Perception check to detect the presence of others is 4d10×10 feet. In hill terrain, the maximum distance is 2d10×10 feet. It’s easier to hear distant sounds in the mountains. The DCs of Perception checks that rely on sound are usually lower at the GM’s discretion.