Elevation: 11,402 ft
Climbing information for this peak is found on page 309. It is not in the book’s index for some reason.
Big Boy Peak sits south of The Riddler on the main Lemhi crest. It is seldom climbed as climbers focus on nearby Diamond Peak. In addition from the route information in the book. The peak has been climbed via a traverse from the Riddler. Details of this route are unknown but from personal observation, the top,of the connecting ridge would be difficult to follow. It looks as though ledges could be connected on the steep eastern slopes between the two peaks to make a high traverse. You could also follow the standard route on The Riddler to around the 10,200 foot contour and then climb steep talus to the summit.
Larry Prescott climbed the east ridge which looks like a great option for ascending the peak. Use the link at the bottom of this page to read his full trip report or go to the East Ridge Route (Class 3) page for a condensed version.