OK so it was a big daypack but, even though I usually carry a small-ish travel pack, this was the lightest I've ever traveled.
Why I did it
I had been through the Guianas (Guyana, Suriname and French Guiana - all on the Caribbean coast of South America) once before so I knew it was going to be rough going in beat up 4WDs or minibuses, over pot-holed muddy roads and I'd perhaps have to hike some distances with all my stuff. I also knew it was going to be hot as hell.
Why I was happy I did it
What I didn't know prior to my trip was that packing such a small bag would allow me to travel quickly and cheaply through southern Guyana via motorbike. This was only possible because my bag was small enough to strap on the back of the bike, thus sandwiching me between my stuff and my driver. Even if I'd had my normal travel pack it would have been too big and I'd of ended up having to pay hundreds of dollars more to charter 4WDs. Packing light gave me freedom, saved me money and let me enjoy some of the most beautiful country I've ever seen in it's full glory.
How I did it
I'd like to tell you that my packing process is highly refined, organized and detailed, but that would be a huge lie. In fact, I was working to deadline on two other Lonely Planet books and finishing up my taxes until the point I walked out my door to the airport. I don't do any of that "pack everything you need then remove a third [or half or whatever]." No, I just very logically think about what I need - not what I romanticize myself needing ("Teach Yourself Dutch" book? Disco shoes? Uh uh). This of course all depends on destination - if I was going to Italy for example and eating out at nice restaurants in a relatively wealthy country where people take fashion seriously, my packing list would have been much different. The Guianas are poor countries where looking too nice makes you stand out and become a mugging target.
What I packed
1 pair lightweight, wicking safari pants that roll up to capris
1 pair more city-friendly capris
1 pair long cotton pants
1 pair lightweight nylon shorts
2 wife beater-style tank tops
2 spaghetti strap fitted tank tops
1 nylon wicking long-sleeve button-up safari shirt
1 long sleeve cotton shirt
1 lightweight casual cotton dress
6 pair undies
2 pair socks
1 lightweight jacket
1 pair hiking shoes
Compact, nylon, mosquito netted jungle hammock
Canon G12 camera
Swiss Army knife
small sewing kit
small travel lock
Everything I needed for showers/personal hygiene I carried in travel-sized bottles to fit in an 8-inch toiletries case.
Big tube o' sunscreen
2 tubes of insect repellent
First aid kit (my own compilation)
Individually packed wet wipes
Tide to Go
Food & Drink
6 Luna bars
water purification tablets (because my Steripen filter is on the fritz)
2 guidebooks (I was there to update a guidebook so had to bring these)
3 ripped out portions of 3 other guidebooks
A big hardcover reading book I promptly lost and replaced with a small paperback
And this was too much stuff. I never used the hammock (I showed it to one of my guides and he laughed at me) so sent it back with a friend after two weeks. I could have done without one of the T-shirts, never used my binoculars and only wore one pair of the socks (I usually hike in flip flops). But otherwise I used everything and was glad I had it. I never wished I had anything more.
How did this differ from how I usually pack?
When I go to countries that have beautiful oceans I pack a mask, small swimming fins and a snorkel. Also, many countries I visit are Muslim, which means I have to cover up more and can't get away wearing my favorite tank tops. I usually pack a pair of ballet flats for nights out and the plane. But otherwise this is pretty much what I bring, just stuffed into a smaller bag.