Mt. Sidley (4,285m). Nowadays, any climbing expedition to inland Antarctica, outside the Ellsworths, is significant. Mt. Sidley, highest peak in the Executive Committee Range, and highest volcano in Antarctica, was first climbed on January 11, 1990 by Bill Atkinson (NZ), who worked as field assistant for a team of vulcanologists studying the area. They also ascended nearby Mt. Wae- sche, mostly on snowmobiles. Atkinson climbed from a camp at 2,380m on the west side of Sidley, reaching, in poor visibility, what he ascertained to be the highest point on the crater rim.

In January 2011 an ALE team made the first non-government ascent. Mike Sharp and Scott Woolums, with Alex Abramov, Mario Trimeri, and Crina Popescu, flew from Union Glacier to the flat ice near Sidley, landing ca 16km from the summit. They then skied for seven hours and made camp on the mountain. The next day, January 24, all but Sharp climbed over sections of soft snow and blue ice to the crater rim. It turned out to be a 13-hour day, as the party continued around the rim, first crossing one top, which they thought was the highest, but later discovering another a few meters higher. They found the terrain quite unusual and ephemeral with snow features along the rim seemingly formed by the mountains thermal activity and then sculpted by the wind. Popescu and Trimeri became the first climbers to attain what they have termed the Seven Volcanic Summits: the highest volcano on each continent.

Damien Gildea, Australia