These are extremely demanding treks, sometimes in very remote areas on rough terrain, and could include (in Nepal) climbs of one or more of the "trekking peaks" (maximum altitude, Mt. Mera at 6461 meters, 21192 feet). Participants should have at least a basic knowledge of the use of crampons and ice axe, though first time climbers may be accepted on some of the "easy" routes. Medical certificates are required for acceptance into these climbing treks.