It is the smallest wilderness in northeast Oregon, encompassing only 20,144 acres (8,152 ha) in Umatilla and Union counties.

[1] The elevation of the North Fork Umatilla Wilderness ranges from 2,000 to 5,400 feet (610 to 1,650 m), and is characterized by terrain that varies from gentle, sloping hills to extremely steep, timbered canyons below a high plateau.

The North Fork Umatilla River supports a sizeable population of bull trout, as well as anadromous fish such as steelhead.

[2][3] Primary recreational activities in the North Fork Umatilla Wilderness include hiking, camping, hunting, fishing, and horseback riding.

[2] There is a 27-mile (43 km) hiking trail system, which opens up early in the season due to the low elevation of the Wilderness.