We drove along the Gallatin River in Montana and were mesmerized by the blue waters, the green vegetation and the lovely mountain backdrops. We did not leave the car. I cannot recommend hikes, but there would be places to picnic if you planned ahead and had deli sandwiches in a cooler with drinks !
The Gallatin River in Montana is what fly fishermen must think about all year ...planning vacations to get here, this place was beautiful. this is where Robert Redford filmed 'a river runs through it' and has a lot of history 120 miles long, one of 3 rivers along with Jefferson and Madison that run through Wyoming and Montana to converge...
This river is both a great fishing area as well as good for whitewater adventures during spring run off. Lots of places for fishing access. Must exercise caution on the lower river when floating or kayaking as deadfall trees into the river create hazards.