Three Mile Trail Fishing Access Site is a popular wade-angler access point on the Bighorn River near Fort Smith, Montana, featuring a well-maintained gravel footpath along the river with easy 2-mile round-trip hiking access.

The site includes parking and pit toilet facilities, making it an ideal starting point for accessing the productive first three miles of the Bighorn River tailwater fishery, though expect crowded conditions during peak season (April-September).