Places to camp along the way: There are 17 camp spots at the trailhead at Big Trinity Lake Campground as well as other spots at the three smaller lakes with road access. These spots are $10 a night. On the trail for overnight backpacking, every lake has at least one great camp spot.
Things to consider: Water is plentiful after the first mile. A good water filter is highly recommended. Mosquitoes can be especially bad in early to mid summer so remember to pack spray. The summit of Trinity Mountain (Idaho’s highest drivable point!) can be reached by a rocky car ride plus a short hike up to the top on the backside of the peak or by a steep scramble from the Rainbow Basin Trail.
Fun places to visit on your way in or out: If traveling through Featherville, stop at the Trinity Mountain Cafe for a tasty burger and fries! There are also hot springs near the river at the Elk Flats campground in between Featherville and Pine.
More info about this hike: All Trails for Rainbow Basin Trail, Forest Service page about the Rainbow Basin Trail, Forest Service page about the Big Trinity Lake Campground