SR-25 runs from the junction of SR-24 near the town of Koosharem northeast to the west shore of Fish Lake.

The byway starts at an intersection with SR-24 and immediately turns north-northeast through mountainous terrain before descending into a basin where Fish Lake is located.

[3] The west end was moved south to Fish Lake Junction in 1935 as a federal aid project,[2] but the legislative description was not changed until 1953.

The Byway was extended in August 1992 between Johnson Valley Reservoir and SR-72 to comprise the southern portion of the Gooseberry/Fremont Road Scenic Backway.

Pando, a clonal quaking aspen stand, that, according to some sources, is the oldest (80,000 years) and largest (106 acres (0.43 km2), 13,000,000 lb (5,900,000 kg)) organism on Earth, is located 1 mile (1.61 km) southwest of Fish Lake on Utah route 25.