Peak 11,050' (Lost Rivers)

Peak 11,050' (Lost Rivers)

Page Type Page Type: Mountain/Rock
Location Lat/Lon: 44.86000°N / 113.518°W
Additional Information County: Custer
Additional Information Elevation: 11050 ft / 3368 m
Sign the Climber's Log


Peak 11,050'+, also known to some as Petros Peak, is located in the Pahsimeroi Subrange of the Lost River Range in central Idaho. This peak may best be desrcibed as having multiple personalities. Its most impressive feature is its breathtaking, vertical 1,600' limestone face that towers over upper terrain of Christian Gulch. The metamorphic processes that formed this stunning feature are easily viewed from the seasonal ponds at the base. Petros Peak's broad and gentle south face contrasts drastically with its rugged east and and steep, talus plagued, west face. Its triple crowned summit adds another interesting feature to this quircky looking peak.

The Pahsimeroi subrange, although not as high or impressive as the heart of the Lost Rivers, are mountains to be taken just as seriously. Their beauty is only outspoken to their terrible quality in rock and difficult access. The area is seldom visited by anyone, let alone a person looking to climb these massive piles of crumbling rock and Petros Peak is no exception. It is not easily approached from any direction and the most direct route involves sketchy scramling not intended for the novice mountaineer. Nonetheless, it is a unique peak that is more deserving of attention among local climbers.

Getting There

Routes begin from Mackay. But how do you get to Mackay? Well, its not easy for most. The nearest airports are in Twin Falls, Idaho Falls, or Hailey. Follow US-93 to Mackay, Idaho at the base of the Lost Rivers.

Continue northward past the Borah Peak Trailhead until reaching a turnoff for Doublespring Pass Road. This is your initial off-road for climbing Petros Peak.

Red Tape

This area is isolated, no two ways about it. Have a full tank of gas, a spare tire and plenty of water as most of the ponds tend to try by July. A four wheel is mandatory for most of the roads.

There are no shortcuts to routes in the Lost River Range, stick to your route or be prepared for a potential nasty outcome.

All roads except US-93 are closed during winter.


There are no official campgrounds in the Pahsimeroi Range. However, there is plenty of room for car camping at along most approach roads and ideal spots in the cirques surrounding Petros Peak for tent camping.

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Children refers to the set of objects that logically fall under a given object. For example, the Aconcagua mountain page is a child of the 'Aconcagua Group' and the 'Seven Summits.' The Aconcagua mountain itself has many routes, photos, and trip reports as children.