Otter is located in the Ashland Ranger District of the Custer Gallatin National Forest in southeastern Montana. The Ashland Ranger District was originally known as the Otter Forest Reserve. The District offers a variety of topography, varying from rolling grasslands, to steep rock outcrops. Vegetation varies from prairie to dense stands of ponderosa pine and offer hunting, solitude, and a good opportunity for nature study as well as picnic and camping facilities.