From Mineral, the byway runs northward through Lassen Volcanic National Park to Manzanita Lake to Old Station.

Thousand Lakes Wilderness and Burney Mountain are located just west of the byway, while Hat Creek Radio Observatory and the Lassen National Forest are to the east.

Continuing northwards from Weed, the byway goes past Carrick, then Pluto's Cave, Mount Hebron, Macdoel, Butte Valley National Grassland, and Meiss Lake before arriving at Dorris.

The byway again splits just north of Dorris; there is an alternate route that runs east for 19 miles (31 km) along the California–Oregon state line on SR 161 past Ainsworth Corner and Lower Klamath National Wildlife Refuge to Hatfield.

At this point, SR 139 becomes the Lava Beds Highway while the Volcanic Legacy Scenic Byway turns sharply to the east.

From Ainsworth Corner, the byway continues east on SR 161 for 19 miles (31 km) through Lower Klamath National Wildlife Refuge along the California–Oregon state line, then turns north onto U.S. Route 97 (US 97) at Dorris.

At Fort Klamath, the byway joins OR 62 and continues north for 16 miles (26 km), where it turns onto Munson Valley Road and enters Crater Lake National Park.