Term: Greater Difficult Terrain

Greater Difficult Terrain is a kind of environmental hazard that comes from extreme weather or bad circumstance. It costs 3 ft to move through 1 ft of Greater Difficult Terrain (or trippling the Movement cost).
Water or brush up to your chest or waist, extreme weather, tar, or fields of crops are considered Greater Difficult Terrain.
The full rules for this can be found at Rule: Difficult Terrains