From May 5-7, 2011, during an acclimatization phase as members of a mostly Slovenian expedition attempting Makalu, Steve House and Marko Prezelj traversed the entire Chago ridge from Peak 6,170m to the col before Makalu II’s northwest ridge.
On the first day they left the 4,800m base camp, walked up the Barun Glacier, and climbed the south ridge of Peak 6,170m, above the old normal base camp at the foot of Makalu’s west ridge. This first, largely rocky, summit is sometimes referred to as Chago Lho III. They continued north to 6,320m Chago Lho I (II is off on a spur to the west), and then onward over the less distinct twin summits of Chago Middle (6,650m, south; 6,768m, north; both first climbed in 1980 by Roger Baxter-Jones, Georges Bettembourg, Ariane Giobellina, and Doug Scott), to Chago (6,893m, first climbed in 1954 by Michael Ball from Hillary’s expedition). From here they went down the east- southeast ridge, over Point 6,723m, to the Chago Shar La (6,588m), where the Chago Glacier rises to meet the frontier ridge. The pair made a first bivouac between Chago Lho III and I, and a second a little past Chago Middle. They consider it a long, classic ridge climb with wonderful views, and if snow and ice conditions are good the technical difficulties are low.
Lindsay Griifin, MountainINFO