Whenever I pack, I always put my important, water-sensitive items in zip-lock bags to keep them dry – things like my passport, camera, and even a large zip-lock bag that I can put my laptop in should the need arise. Doing this gives you some assurance that if you’re ever caught in a downpour, these items will remain safe and dry even if you get drenched.
This can be of greater importance if you’re going to an island or other destination where boats are used for local transportation. Even in mildly choppy waters, an awful lot of water can spray into smaller-sized boats, soaking you and your luggage or backpack. If you’re ever caught in this situation and happen to have a rain poncho, you might consider wrapping it around your bag instead of yourself, but you should still keep your key items in zip-lock bags, as the other risk to your camera comes when getting in our out of a boat: one wrong move and your bag could take a dunk, as happened to a friend of mine while she was traveling in India. While zip-lock bags are not ideal waterproof bags, they cost next to nothing, and your camera will probably be fine as long as the zip-lock is sealed and you grab your bag quickly, before it becomes fully submerged (and even if that happens, your camera will likely still be fine).
This is a great use for used zip-lock bags: ones that you aren’t quite comfortable re-using for food items, but are clean enough after a quick rinse to put your camera or passport in for the sake of keeping things dry. You don’t need to limit their use to cameras and passports, either: I use them to keep small items organized within my bag. You can also make use of the bags when you reach your destination: keep crackers, cookies or other snack food in them for freshness and to keep out ants – something especially important if you’re in the tropics.
To further protect your gadgets and other water-sensitive items, throw a adsorbent silica gel packet, which often come with new electronics and vitamin supplements, into the bag with your camera or mp3 player. These packets are included with such items because they soak up humidity which can damage electronic components – and they can serve the same purpose when traveling in humid environments or if your bag gets soaked. They’re lightweight and free, as long as you remember to hang on to them when you get them.
If you’ll be spending a lot of time on the water and need some serious water protection, definitely look into a proper waterproof bag that’s designed for the job, otherwise known as a dry bag.