I don't get wearing a large pack for in bounds skiing, but I've found that a hydration pack is a necessity for me. It's a low profile one that holds a couple of other things like googles and some energy bars. It has none of the extra compression straps that usually hang off the back of a skiing day pack even so, on some lifts I will swing take one arm out and swing it to the side. Looking at my Dakine Heli pack which is reserved for the occasional out of bounds touring, I really would hesitate to wear it on a lift given all the straps and loops.