Consider wearing your heaviest and bulkiest items on the plane rather than packing them.I mentioned hiking boots earlier. If I'm off to Colorado to do some hiking, I would most likely wear my hiking boots on the plane. I'm almost fanatical at times about figuring out "how light can I go?"

<--- Ok... So, here is a real picture of what I wore on a plane recently (to St. Maarten).

I was leaving Boston in cold weather, so I knew I would need something a little warmer than my island clothes for going to and from the Boston Logan airport. I also didn't mind having a sweatshirt with me (even though it wasn't likely that I'd need it), and I knew we would be hiking over to a secluded beach on a fairly rough trail (cactus, hermit crabs, sticky thorns...), so the sneakers were a prudent addition to the clothing.

John was dressed similarly. Only he's even MORE fanatical than I am. Under his trousers, he actually wore a pair of the shorts he would be using for hiking AND swimming. Wow. That's extreme! Even I don't go that far... :)

So, I KNOW that you can't wear your dive fins or your ski boots on the plane. Or your wetsuit or ski overalls. And I KNOW that you can't layer your toddler in 20 diapers to save room in the bag. All I'm saying is to just think a little differently about packing and dressing. Maybe you could wear the bulky sweater instead of packing it (it might come in handy on the plane as a pillow!).

Stuff like that. 

Now, getting back to what I wore. I actually folded it all up, stacked and measured it to show you how much room it would have taken in my carry-on bag. It was stacking up to about 8-inches high. It also weighed quite a bit. Here is the result: