Summit day! Very long tough day. Set alarm for 3:30 aiming to be off by 4:30, but mostly due to me, we don't get going till 05:00 with headlamps. Steady plod with crampons up a steep slope to the old Indepencia camp (a couple of snow-filled wooden shacks), then the long traverse (quite exposed) to The Cave, where we take a good break and leave our big packs, just taking essentials to the summit (should have had a very small summit pack here). Every step is an effort! Several more large steps (rock bands), till the summit, which is relatively large and flat. of course the light snow means there is no view, but it's mild and not too windy. Only spend about half an hour on the summit as we are all tired. Huge effort to get back to C3. Everyone is very tired. Steve and Alicia seem to need short roping down. Then we get to the cave we pick up out packs and are fitted with make-shift lanyards to attach outslves to fixed lines which have been placed on the steepest section after the recent fatalities. Towards the end of the return to C3, there were quite a few in other groups so tired they were just keeling over and not getting up again without help.