Mann Gulch is a gulch in the Gates of the Mountains Wilderness of the upper Missouri River, north-northeast of Helena, Montana, in southeastern Lewis and Clark County. It is on the east side of the Missouri River and approximately east of Interstate 15 (I-15), between Helena and Wolf Creek. Mann Gulch is between Meriwether Canyon immediately to the south and Rescue Gulch immediately to the north, and the creek it contains flows into the Missouri in the canyon known as the Gates of the Mountains. Mann Gulch is approximately southeast of Beartooth Mountain.