Back in February a couple of us took a week long trip to Hawaii. Since we were trying to do it as cheap as possible, we all decided to just take carry on luggage.
I am typically not the best packer. Even when I try to pack small, I can never zip my luggage without some kind of squishing happening. I started looking for ways to best pack small, and came across a lot of tutorials on how to roll your clothes to pack them in tight. Which is also how my father taught us how to pack when we were little. However, I still have trouble fitting stuff in, even when I rolled everything.
Then I came across something called "flat packing" where you lay everything as flat as possible...this method is pretty much MAGIC!
Using this method, I was able to pack the following into a carry on;
3 Pairs of Pants
2 Swimsuit Coverups
3 Pairs of Socks
1 Beach Towel
2 Pairs of Shoes (I wore a third on the plane)
All my toiletries
Snorkel Set (Fins, Mask, and Snorkel)
Below is a great video showing this method. I hope it helps you as well.