Rainbow Ridge is the local name of the ridge which rises from the Rainbow lakes basin in the Trinities (hence the name). The ridge has two points almost equal in height: point 9135 and peak 9140, the high point by 5 feet.
Peak 9140 is a minor summit, but notable for two reasons. The first is its sheer northwest face, which drops several hundred feet into the lake basin below. The second is that this is a good place to find solitude in an area which sees quite a bit of activity.
Due to the wide-open nature of the area, the peak is approachable from a number of directions, with the most straightforward being a scramble from the lakes south of Trinity mountain.
The Trinity area, although low in elevation, receives a large ammount of snow. The road often does not open until July. Due to the long access, it is primarily a summer use area.
Getting ThereThe Trinities are not far from Boise (less than 45 miles as the crow flies) but the drive is long and circuitous. Take Interstate 84 east to Mountain Home, and highway 20 toward Fairfield. Before you reach Hill City, take the turnoff for Pine and Featherville. This road is paved for many miles as it winds its way along Anderson Ranch reservior. Pass through Pine. One mile short of Featherville, turn off the paved road onto an improved dirt road, following the signs directing you to the Trinity area. It is approximately 18 miles on good quality dirt roads with signs all the way.
Other ActivitiesEven with the high traffic in the area, there are many lakes in the area, so it's easy to get away from people. Most of the lakes offer decent fishing and there are ample opportunites for ridge walking and scrambling.
The faces of 9140 and point 9135 are sheer and drop several hundred feet into the basin, which is a rarity in the Boise mountains. There may be some attractive climbing lines here, but I cannot vouch for the quality of the rock.
CampingAt the Big Trinity Lake, there is plenty of pay camping. Be aware that this is a high use area, so on weekends you will be competing for spaces.
There are many lakes in the area which offer good backpacking destinations.
External LinksTom Lopez's Idaho: a Climbing Guide remains the best guide for Idaho's peaks.
Boise National Forest website
There is a Snotel site at Trinity Lake, handy for checking conditions.
See Super Dave's 2008 trip report into the Rainbow Basin.