<p>Notwithstanding the sensible advice regarding going in and out of A/C etc, air conditioning is actually your best friend when dealing with sensitive equipment in high humidity. A/C makes the air very dry and there's nothing better for your equipment than regularly leaving it for a few hours in a well air conditioned room when you're in the tropics.<br>
Also store all your equipment with lots of silica gel bags everywhere (make sure these get the a/c treatment as well so they dry out too).<br /> Lastly I don't know if you're out there during the rainy season or not but you might want to consider taking a drybag also (just big enough to put your camera bag into should you get caught). Normal camera bags are inadequate in tropical conditions but once in a drybag it could survive a river - I find Ortlieb the best brand. <br /> This advice is equally useful for digital as well as film but good for you taking some film out there, you will see a huge difference from your previous photos and you won't regret it, just make sure you take enough!</p>