I spent nearly 18 months backpacking through SEA and India & have spent a fair amount of time pondering the contents of my backpack. Here is my Top Ten of "Must Haves" when traveling to a sunny island paradise, or anywhere.
1. Headlamp or torch. Streets & paths on Gili Trawangan (and most small islands) are not lit. Power outages can also be quite common especially in high season when the power grid is stressed.
2. Sunscreen. For some reason sunscreen is ridiculously expensive here and with bright sunny days you don't want to run out of sunscreen
3. A comfortable hat.
4.Compression sacks. Compression sacks can take loads of stuff and compress it into a tiny disc. Pure Magic.
5.Quality water shoes. Shoes like Tevas, Chacos. etc. cannot be found in asia. These a great for walking over coral rubble as well scrambling up a hill or two, if that's your thing.
6. UVA/UVB sunglasses. While asia is chock o block full of knock off Pradas, sunglasses that actually protect your eyes are expensive & nearly impossible to find, except in larger cities.
7.Smart phone. Smart phones are a great way to stay connected to friends & family, book plane tickets, use email..... the list is endless. Sim cards are cheap & readily available throughout SEA. *if you live in the US be sure to ask your carrier to unlock your phone before you depart
8. Ibuprofen. Ibuprofen is a handy anti-inflammatory great for all those bumps & headaches you get when traveling, In most of Asia you will have to find a pharmacy with a live pharmacist to dispense it and it will be more costly than in the West.
9.Kindle or EReader. I was a late adopter, but now I am smitten. Books are heavy to lug around (Shantaram) and books you actually want to read are hard to find in book shops/exchanges.
10.Sense of humor. No matter where or when you travel, something will go wrong. Guaranteed. How you perceive the mishap is up to you. Lighten up. Be happy. Be grateful. Be gracious.