Hill

difficult terrain; rises 5ft per ring — high ground gives advantage, and a taller hill blocks sight unless you stand above it

Forest

blocks movement and line of sight — no shooting through the canopy

Rocks

impassable; half cover behind them; formations rise 10ft per ring

Mountain

a rock core above 30ft (snow-capped) — walls off sight completely unless you stand even higher

Water

difficult terrain (wade at half speed); swimmers cross freely; bridges span it

Swamp

boggy difficult terrain — half speed through the mud

Road

clear, fast ground — full speed

Pit

a sunken hole — difficult terrain to clamber through

Wall

impassable and blocks sight

Door

openable when adjacent; some are locked (break them), trapped, or SECRET — hidden in the wall until a Survival sweep finds them

Barrel / crate

blocks movement; grants half cover (+2 AC) behind it

Trap

hidden until it springs — a Survival sweep (bonus action) reveals traps within 15ft

Chest

loot — open it when adjacent and pick one of three treasures